Windows only: Portable utility Mute on Lock turns off your system speakers whenever you walk away and lock your workstation, but it also provides a quick shortcut key for toggling your speakers on or off.

Once you've downloaded and launched the no-installation-required utility, your speakers will turn off immediately after pressing the Win+L shortcut key to lock your workstation, and then turn back on once you've unlocked your PC. If you head into the settings page, you can set up a custom shortcut key to mute or unmute the sound, or customize what the tray icon does. Definitely a handy utility for those of us that lock our workstations religiously, and it doesn't take up a lot of resources either.

Mute on Lock is a free download for any version of Windows, though readers should note that you might have to use the Windows Compatibility Mode feature set to Windows XP to get it to work properly on Windows 7.

Windows/Mac: Unfortunately the iPhone and iPod touch lack the ability older iPods had to run in Disk Mode. That's where iPhone Explorer steps in, allowing you manually manage files on your device, or just use it as a flash drive, without jailbreaking.

iPhone browser is a lightweight application that has an easy drag-and-drop interface that lets you browse the contents on your iPhone. You can manually transfer your photos, music or movies from your device back to your computer, or just add files to the iPhone and fill up the unused space as extra storage. There's even an image preview for transferring photos. The best part about the whole thing, though, is that you don't need to jailbreak to use it. If you do have a jailbroken device, though, iPhone Explorer becomes even more useful—It can access the root of jailbroken phones and browse the files inside, with no need for complicated SSH setups.

The only issue I had was that multiple selection didn't work so well—whether I was trying to transfer files to or from my iPod touch, doing it one file at a time worked much better than trying to do more. So if you need to transfer large batches of files, you may be better off putting them in a folder beforehand to avoid crashes.

iPhone Explorer is a free download for Windows and Mac OS X 1.5+, requires iTunes 8 or 9 to use.

Windows only: LookInMyPC generates a complete report of what's going on in a computer—from hardware to software, and everything in between. After playing around with it, this writer wouldn't start troubleshooting a PC without it. I'm not kidding.

Whether you're a tech guru who knows your way around your computer better than the company that built it, or a novice just getting acquainted with your system, LookInMyPC is a free app you'll want to download and run at least once, even before you need its diagnostic help. It's like a big verbal X-Ray of your PC, detailing everything from the brand of network adapter you have to the number of user accounts on your system.

Everything that a LookInMyPC report generates can already be found in your computer's accessible files if you know where to look, but this utility makes it so much easier. Just open the system inspector and tick the boxes to select all or some of the more than 40 diagnostic checks you want it to perform. Seconds later, you'll have a long report outlining every detail LookInMyPC ferreted out for you. Stash it in a drawer with your computer's owner's manual for a fast and handy reference sheet the next time you need to know what brand sound card you have or what the specs are on your processor.

LookInMyPC is also a great tool for diagnosing computer issues, especially if you're troubleshooting an unfamiliar computer. Instead of spending time poking around your uncle's PC to figure out basic system information, just generate a general report with memory and operating system information, then get down to business. Once you have a feel for what issues you're trying to correct, you can generate more specific reports like Registry Run Entries or Firewall Info. LookInMyPC even gives you data on Windows updates, recent System Restores, and the default email client.

The utility won't make any changes to your system at all, no matter what issues it identifies. The reports open up in a browser window and many of the results—like system hardware vendors and application names—are hyperlinked so you can quickly Google-search things you don't recognize.

One really nice touch that's included in this app is the ability to generate a report that automatically turns itself into a ZIP file and emails it to the address of the user's choice. That's a huge help when you get a distress call from a relative who wants you to troubleshoot his computer remotely.

LookInMyPC is designed to work with Windows 2000, 2003, XP, and Vista, but we ran it on Windows 7 with no issues. Pair this app with screencasting webapp ShowMeWhatsWrong and you'll be the neighborhood PC go-to person in record time. What apps and tools are already in your troubleshooting toolkit? Know of a similar solution, like previously mentioned SIW? Tell us in the comments.

Windows: Ever download a movie from—oh, I don't know—some far-reaching nether-region of the internet, and when your download finishes realize the video is split into multiple parts? AVI Joiner quickly combines those split videos in just a few clicks.

Using it could not be easier. Just run the app (AVI Joiner.exe), drag and drop the files you want to join into the Files to be joined pane, make sure they're in the correct order, and click the Run AVI Joiner button. The app will ask you where you want to save the joined video (name it and make sure to add the .avi extension to the end), then sit back as it fires up a command line and starts the joining process. I joined a couple of 700MB files into a 1.4GB video in roughly a minute.

This awesome little app was built courtesy of the Lifehacker Coders group over at the Productive Geek forums. You can currently grab the download hosted over at drop.io here. We reached the download cap—get the ZIP here instead. (For a portable version, grab the AVI_Joiner.zip file; if you want an installer, grab the setup.exe and install.nsi files. Make sure you grab the newest versions, and if we happen to hit a bandwidth cap at drop.io, be sure to let me know.)

AVI Joiner is a free, open-source application for Windows only.

Windows only: Spyware removal tool SUPERAntiSpyware has finally released an official portable version of their application, and, just like the installed version, it easily removes most infections on your PC in a single swipe.

Once you've downloaded the application, the first thing you'll probably notice is the weird filename—each time you download it you'll be given a random filename, because most of the worst malware will prevent you from opening or installing any known malware removal tools. You'll be prompted for the language and a start screen, and then you can scan the infected PC immediately—the latest definition updates come with the download.

We've featured SUPERAntiSpyware before as one of the best malware removal tools, but the addition of a portable version makes it well worth a look for anybody with a machine infected with spyware. I've personally used this tool a dozen times to remove many different fake antivirus infections like Antivirus Live, and it's never let me down.

SUPERAntiSpyware Portable is a free download for Windows users. Click the link for the download, or check out the full screenshot tour over at How-To Geek.

Windows only: The newest version of the popular Avast Antivirus is finally available for download. It's lighter, faster, and more feature-filled than ever, bringing a new behavior shield, heuristics engine, and code emulator to keep you protected at all times.

Apart from its far easier-to-navigate interface, Avast has a few new features that make it hard to turn down. Its new code emulator can emulate a suspicious executable's code, isolated, for use in its new heuristics engine, designed to detect malware that would otherwise be undetectable with normal definitions—in other words, spotting malware by learning what the code does. If you use the pro version, you also get their new sandboxing feature for even further protection.

Apart from the new features, Avast has also lowered scanning times as well as the resources necessary to scan and update—a common issue with antivirus programs that are always running in the background. If you're already an Avast lover (and many of you are), you can either wait for the program to update itself in the near future or go download 5.0 straight from Avast. If you've tried Avast and turned it down before, it may be worth another look—you may find that its former cons (such as the difficult-to-use GUI and resource use) are now more up to your standards.

Avast Antivirus is a free download, Windows only.

Windows only: The newest version of the popular Avast Antivirus is finally available for download. It's lighter, faster, and more feature-filled than ever, bringing a new behavior shield, heuristics engine, and code emulator to keep you protected at all times.

Apart from its far easier-to-navigate interface, Avast has a few new features that make it hard to turn down. Its new code emulator can emulate a suspicious executable's code, isolated, for use in its new heuristics engine, designed to detect malware that would otherwise be undetectable with normal definitions—in other words, spotting malware by learning what the code does. If you use the pro version, you also get their new sandboxing feature for even further protection.

Apart from the new features, Avast has also lowered scanning times as well as the resources necessary to scan and update—a common issue with antivirus programs that are always running in the background. If you're already an Avast lover (and many of you are), you can either wait for the program to update itself in the near future or go download 5.0 straight from Avast. If you've tried Avast and turned it down before, it may be worth another look—you may find that its former cons (such as the difficult-to-use GUI and resource use) are now more up to your standards.

Avast Antivirus is a free download, Windows only.

Windows: If you want a solid overview of what computers, networked printers, and other resources are available on your network, NetResView is a free, light weight, and portable application for doing so.

NetResView is a stand-alone application capable of scanning your network and showing you all computers, printers, shared folders, and other network resources available on domains and workgroups your computer is connected to. From the NetResView interface you can see the resource name, type, what workgroup or domain it belongs to, its IP address, a local path if it's on the machine you're working on, the MAC address of the machine, and other information.

You can restrict the scope of the search by excluding information like the individual shares on each machine—noticeable increase in speed—or restricting the search to only a certain domain or workgroup if you're on a particularly large network and a portion of the network is irrelevant to your search needs. The information generated by NetResView can be saved as an HTML report. NetResView is freeware, portable, and Windows only.

Firefox with Windows only: While traveling the internet, sometimes we don't realize how much memory our browser is hogging until it starts acting sluggish, hangs, or crashes altogether. Firefox extension Memory Fox optimizes your memory so you can surf without slowing down.

Memory Fox keeps an eye on your browser's memory usage and notices when Firefox starts edging toward user-preset resource limits. When it does, the extension springs into action, automatically flushing your memory to recover space and keep your browser from slowing down.

To use the add-on, you need two things: A Windows operating system and Firefox 3. Once you download the tool, restart your browser then activate Memory Fox from the Tools button in the toolbar. Now the add-on is all set up to flush the memory every time you open or close a tab, or switch between tabs.

Memory Fox may not make a noticeable difference in your browsing speed if you've got a souped up computer, but it's a terrific add-on for machines without a lot of extra RAM to sacrifice to the 'fox. It's an experimental extension, Windows only. If you give it a try on your memory-hungry Firefox installation, let's hear how it works out for you in the comments.

Windows only: Planning an upgrade soon? Save yourself the web searches for your specs and download Speccy. Speccy does a quick scan of your machine and gives you a complete rundown of every piece of gear that's in your computer.

Upon first glance, Speccy seems like something that's only attractive to power users, but it can be useful for anyone. When the Device Manager doesn't give you enough information about what kind of RAM you have (say, if you're looking to upgrade), Speccy will give you all the information you could possibly need, including the RAM type, how much you currently have, and even the number of slots used so you can buy with confidence.

You can view your computer's information in a brief summary (as shown), or click on any of the categories for a very, very detailed report. Speccy gives you detailed information for CPU, motherboard, graphics, hard drives, optical drives, and audio, all so you don't have to go searching somewhere else to find out what you have. In addition, it also gives you real-time information on things like bus speed, DRAM Frequency, and temperature, to name a few.

We've featured one or two different tools like this in the past, but thus far, this is the cleanest and most detailed one we've used yet. Speccy is a free download, Windows only.