CCleaner cleans out unnecessary files that not only take up space but can impact performance. Fully configurable and of course, FREE!
Here's what it found on my 3 year old computer:
Yes, that's an astonishing amount of unneeded clutter. In the end it removed about 7 gigabytes of files though you will probably not see these kind of results.
I should note that the next time I ran it the scan was completed in under 3 seconds
Removes, among other things (From the site):
From Firefox, Internet Explorer, Opera:
Temporary files, URL history, cookies, Autocomplete form history, index.dat.
From Windows:
Recycle Bin, Recent Documents, Temporary files and Log files.
Registry cleaner
Advanced features to remove unused and old entries, including File Extensions, ActiveX Controls, ClassIDs, ProgIDs, Uninstallers, Shared DLLs, Fonts, Help Files, Application Paths, Icons, Invalid Shortcuts and more... also comes with a comprehensive backup feature.
Third-party applications
Removes temp files and recent file lists (MRUs) from many apps including Media Player, eMule, Kazaa, Google Toolbar, Netscape, MS Office, Nero, Adobe Acrobat, WinRAR, WinAce, WinZip and many more...
100% Spyware FREE
This software does NOT contain any Spyware, Adware or Viruses.
Link
Meebo is a free web based instant messager that allows you to sign into aim, Yahoo, Google talk or msn, all for free and in your broswer. Great for use in internet cafes that don't have your IM software installed. 
Pepsky Free Audio Converter will allow you to create a standard or MP3 music CD from any number of formats. It also does a lott more, like simple audio file conversion and CD ripping.
