The best part is that it's fast! (normally taking less that a second to run) and Free.

CCleaner cleans the following:

· Internet Explorer: Temporary files, URL history, cookies, Autocomplete form history, index.dat.
· Firefox: Temporary files, URL history, cookies, download history.
· 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 Opera, 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.

CCleaner comes in 3 flavours :

• CCleaner Standard which contains the Toolbar and extra languages
• CCleaner Slim which contains No Toolbar & English Only
• CCleaner Portable which contains the normal CCleaner program, but it doesn't require installing.

What's New in CCleaner 2.08.588:

· Added Startup tool enable/disable checkbox.
· Fixed problem with Vista "low" folders being removed.
· Improved index.dat detection on multiple scans.
· Secure deletion improved with IE History index.dat files.
· Added OS detection to INI files.
· Added Vista Thumbnail Cache cleaning.
· Added ImgBurn cleaning.
· Added Secure deletion to "Recent Documents" cleaning.
· Improved Vista "Recent Documents" cleaning.
· Fixed bug with Chkdsk chk files not being removed.
· Added "Select all" checkbox to header of Registry cleaner.
· Added sorting to Startup tool listview.
· Fixed Vista 64 issue with Startup tool.
· Added Croatian translation.
· Minor tweaks and GUI improvements.