Most people covered the common software out there, so I’ll focus on the less commonly mentioned programs and stuff outside of Ninite.
All free and for Windows XP/Vista/7 (unless otherwise noted):
If you are coming from Mac or Linux and really miss the virtual desktop feature in Windows, then I would recommend Dexpot. Its free and has tons of features and supports multiple monitors. VirtuaWin is also free (and open source) and is lighter on system resources but has far less features than Dexpot.
If you have multiple monitors and wished each monitor had its own taskbar, then I recommend Zbar. It is free unlike UltraMon, DisplayFusion or MultiMon.
If you love tabbed web browsing and miss it in Windows Explorer, then I recommend QT TabBar. It adds tabs right into Windows Explorer rather than being a full blown explorer replacement (such as Better Explorer, xplorer2, total commander, explorerXP). Its free and opensource which is always a plus.
If you want a more feature filled ALT+TAB replacement, then I recommend VistaSwitcher. Ignore the name, its compatible on Win XP/Vista/7.
If you are a security nut and want to go above and beyond just an antivirus and firewall, I would recommend Sandboxie. It is a application that will allow you to run software (such as your web browser) in a sandbox. This means that any program running in the sandbox cannot make permanent changes to your computer. So if you run your web browser in Sandboxie and you accidentally download a virus, the virus is stuck inside the sandbox. The free version has some restrictions but gets the job done.
CCleaner (free windows temp file cleanup utility by Piriform), used to be on Ninite but got taken down due to disagreements between the two companies. I have not seen this program mentioned yet, which is weird because its super useful in freeing up wasted space. In fact, all of Piriform’s programs are a must have.
SpywareBlaster is a different kind of antispyware program. Rather can scanning your computer for spyware that you might accidentally acquired, this program tries to prevent spyware from being downloaded in the first place. It does this by updating your web browser’s list of malicious sites.
If you ever got the annoying message that a file cannot be deleted because its being used by another person or program then you will love The Unlocker. Its only purpose is to delete files that are locked by Windows. Its free and comes in handy all the time.
If you own an ereader, then I would recommend Calibre. Its like iTunes but for ebooks. It is also free and opensource and runs on windows, mac and linux. Also, if you look carefully, there are unofficial plugins that remove any drm from your ebooks.
If you download a lot, I would recommend jdownloader. Yes, its written in Java but has a lot of useful features (including rapidshare and captcha support). Its also free, opensource and available on Windows, Linux and Mac.
Process Explorer is a free Task Manager replacement that is way more useful than the default windows task manager.
If you download illegal/greyarea/copyrighted files frequently, there is a program PeerBlock that blocks known IP addresses from organizations like RIAA and MPAA. It is debatable how helpful this program truly is since the RIAA/MPAA can just grab new IPs, but it wont hurt to run it. Its free and open source.
For laptops and smartphones I recommend Prey. Its a free and open source “lojack” which will come in handy if you ever lose your laptop/smartphone. If you already lost your Android phone, I recommend Plan B. It can be downloaded to your phone after you lose it which may be helpful if you didnt have a program like Prey installed.
While Notepad++ constantly gets mentioned (as it should, its awesome), sometimes its overkill for simple text editing. While the default Windows notepad is horribly bad at everything, I find Notepad2 to be a good compromise. Its small, light and open source. I end up replacing the Windows notepad executable with the notepad2 executable.
XP-Antispy is a free nifty little program that can turn off/on hidden Windows settings (settings that tend to be somewhat related towards privacy/security/performance). Dont be put off by the name, its compatible on Win XP/Vista/7.
While both Foxit and SumatraPDF seem to be the two most recommend pdf viewers, I like PDF Xchange Viewer. Although its not as popular, I find it to be lighter than Foxit but just as good with just as much functionality.
FolderMenu is an awesome little tool that provides context menus allowing you to easily navigate to your frequently used folders/programs in one click. It is fully customizable so you can add your own entires into the context menus.
If you hate that Windows Explorer does not list the size of folders, then FolderSize is for you. Its free, opensource and integrates directly into Windows Explorer. XP only, as Vista/7 removed the API/hooks that this software utilizes.
If you would like an easy way to customize the right click menu (remove useless entries, add your own), then I recommend FileMenu Tools.
Its a plugin, not a program, but if you like RES, then you will probably like SocialFixer. SocialFixer is to facebook what RES is to Reddit. Its available for Firefox, Chrome, Safari and Opera. Sorry IE.
Photo by Teuobk