Whether you're hunting for a DLL file, the perfect font, or an invite to that hot new beta Web service, these sites can help.

afreeDLL
Hunting for a DLL (Dynamic-Link Library) file? afreeDLL makes finding, downloading, and restoring .dll files a breeze, and all of the downloads are free. You can browse the site's most popular files or search alphabetically, and the site includes explanations and tutorials to walk you through the download and installation process.

DaFont
The site does what its name implies: It collects the coolest, freshest fonts you'd ever need. DaFont features almost 7,500 fonts, all uploaded by various users worldwide. Site navigation is straightforward: Simply browse for fonts either by the categories listed at the top of each page, or by searching for a font name. Most of these free fonts are compatible with both Macs and PCs.

DZone
DZone is a developer's dream-a vast network of user-submitted links to message boards, news, coding tricks, and more. The DZone Snippets section is the "ultimate community source clipboard" for everything from Java to C++. If you're looking for new tools, tips of the trade, or just some dev-centric lunchtime reading, a quick DZone scan will put you on the right path.

Infected or Not
Panda's Infected or Not service offers the excellent (and free) NanoScan tool to ascertain quickly whether there's malware on your machine, and it also tracks PC infections around the world. Get the data on both active threats and latent threats, and find out what percentage of scanned PCs have gunk on them.

InviteShare
Don't you hate when the coolest new Web services are by-invitation-only closed betas? For those who aren't on the invite list or aren't friends with A-list bloggers, InviteShare is your ticket in. The free service lets those lucky early beta users share their invites-and the more you share, the more likely you'll be to get the invites you crave. So scoot on over there, help someone else to some of your beta spoils, and grab your ticket to try out Joost, Pownce, or ImInLikeWithYou.

MajorGeeks
Is your PC behaving badly? Let the geeks at MajorGeeks.com handle the situation. The site has a collection of free and paid apps and utilities for your PC that have been tested to recover, repair, protect, back up... the list goes on and on. Sort files by name, date, license, OS, or popularity.

OldVersion
The site's motto says it best: "Because newer is not always better." Everyone's encountered new versions of products that add unnecessary features, turning a lean and effective tool into slow and bloated crapware. Or worse: a new version that's simply incompatible with other apps you need for daily use. Roll back to the good old days with OldVersion.com! Need QuickTime 2.0? OldVersion.com has it. Unhappy with AIM's newest beta? Switch back to 5.9. Chances are, if you want it, OldVersion's got it.

ProgrammableWeb
ProgrammableWeb keeps tabs on mashups and open APIs across the Web. When a service such as Google Maps, Flickr, or Facebook opens its API, ProgrammableWeb is one of the best resources for finding new extensions or building your own.

Website Grader
Want to find out how effective your blog or Web site is at snaring all-important search traffic and inbound links? Submit your URL (and your competitors' URLs) to Website Grader, which gives you some basic feedback on how your site is doing and in what areas it can improve. It's a free way to get advice on optimizing your site for search engines, which can drastically boost your traffic. Just enter in the URLs and Website Grader will do a quick (but thorough) analysis.

These geeky sites give users the tools and info to do it themselves, whatever "it" might be.

AVS Forum
AVS stands for Audio Video Science, but the AVS Forum is much more fun than the name sounds. Home theater buffs, audiophiles, and high-def junkies will feel right at home on the extensive forums, whether offering advice to others or getting tips to improve their own home-entertainment setup.

Distro Watch.com
DistroWatch.com has the Herculean task of keeping pace with the many-headed hydra that is the open-source community. The site includes reviews, articles, and links to the latest Linux distros, from Ubuntu to Red Hat Enterprise to the most niche open-source OS.

Extreme Tech
If PCMag.com is the site for people who buy cutting-edge PCs, ExtremeTech (also owned by Ziff Davis Media) is the site for people who build cutting-edge PCs. The site has tons of component reviews, news, and first-hand tales of technology from ET's staff of geeks, hackers, and DIYers. There's also an active community in the site's forums, ready to lend expert advice to other readers.

Instructables
Do you know the super-secret steps to make a bike out of an office chair? A glowing Green Lantern ring? Invisible book shelf? There's no DIY project too technical, artistic, or edible for Instructables. Some are more useful (magnetic power connectors) than others (full-size hovercraft), naturally. Each step comes with an annotated picture-occasionally a video-and each project has user feedback, occasionally with an improvement. Share your super-secret project today.

ProcessLibrary.com
What the heck is crss.exe? pmmon.exe? isass.exe? You're computer-savvy enough to know they're executable files, but if you check them out on ProcessLibrary.com, you'll see that they're extremely dangerous. ProcessLibrary.com translates gibberish process names into familiar English, letting you know if isass.exe is malicious or not (it is), and how you should handle it (disable and remove immediately). Simply type the unfamiliar process or DLL into the site's search box, and you'll get a security rating, description, and recommended action.

Version Tracker
Version Tracker is among the most popular resources out there for Windows, Mac, and Palm software upgrades, patches, and updates. It's also for users who want to roll back to an earlier version of an app because the current one has a finicky feature we don't like or is just a tad too buggy. The site also lets you stay on top of updates, patches, and more with the Version Tracker blog.

Lifehacker
The preeminent DIY blog, Lifehacker covers everything from tweaking your PC settings to organizing your home. If there's clutter, disorganization, or inefficiency in your life, work, family, or computer, Lifehacker has the solutions (with diagrams).