CCleaner is a freeware system optimization and privacy tool. It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. But the best part is that it's fast (normally taking less than a second to run) and contains NO Spyware or Adware! 

ChangeLogs:

- Firefox 3.0 support added.
- Fixed bug where figures were missing for KB/MB sizes.
- Fixed bug where some IE cookies were being missed.
- Improved scan time accuracy.
- Internal memory management improvements.
- Registry settings moved to HKCU\Software\Piriform\CCleaner.
- Fixed bug where CC could get locked in System Tray.
- Renamed MSN Messenger to Windows Live Messenger.
- Added MS Office Picture Manager to applications.
- Fixed uninstaller tool bug on 64-bit OS.
- Minor GUI improvements.
- Minor bug fixes.