Copied from CCleaner Homepage:
Features
Program Summary:
CCleaner is a freeware PC optimization tool.
It combines a system cleaner that removes unused and temporary files from your system and also a
fully featured registry cleaner 
CCleaner allows Windows to run faster, more efficiently and gives you more hard disk space.
The best part is that it s Small, Fast and Free  
 Cleans the following Windows components:
   Internet Explorer  
- Temporary File Cache 
- URL History 
- Cookies 
- Hidden Index.dat files 
- Last download file location 
   Firefox  
- Temporary File Cache 
- URL History 
- Cookies 
- Download manager 
   Google Chrome  
   Opera  
   Safari  
   Recycle Bin 
   Clipboard 
   Windows Temporary files 
   Windows Log files 
   Recent Documents  on the Start Menu  
   Run history  on the Start Menu  
   Windows XP Search Assistant history 
   Windows XP old Prefetch data 
   Windows memory dumps after crashes 
   Chkdsk file fragments 
Advanced Options allow cleaning of:
   Menu Order cache 
   Tray Notifications Cache 
   Window Size and Location Cache 
   User Assist history 
   IIS Log Files 
   Custom Folders 
Application Cleaning:
As well as cleaning up old files and settings left by standard Windows components, CCleaner also
cleans temporary files and recent file lists for many applications. Including: 
   Firefox, Opera, Safari, Media Player, eMule, Kazaa, Google Toolbar, Netscape, Microsoft Office,
Nero, Adobe Acrobat Reader, WinRAR, WinAce, WinZip and more... 
Registry Cleaning:
CCleaner uses an advanced Registry Cleaner to check for problems and inconsistencies. 
It can check the following: 
   File Extensions 
   ActiveX Controls 
   ClassIDs 
   ProgIDs 
   Uninstallers 
   Shared DLLs 
   Fonts 
   Help File references 
   Application Paths 
   Icons 
   Invalid Shortcuts and more... 
Safety:
CCleaner was designed from the ground to be safe and secure to use. It has multiple levels of
checks in place to ensure that it cannot delete any useful information or documents you may still
need. We also certify that it contains no Spyware or Adware. 
High Security:
For the super cautious users we also offer secure file erasing. By overwriting the files before
deleting them, making it impossible to recover the data. 
Multiple Languages:
Thanks to the translators, CCleaner is available in 35 different languages: 
English, Albanian, Arabic, Bosnian, Bulgarian, Catalan, Chinese  Simplified , Chinese  Traditional
, Czech/Slovak, Danish, Dutch, Finnish, French, Galician, German, Greek, Hebrew, Hungarian,
Italian,
Japanese, Korean, Lithuanian, Macedonian, Norwegian, Polish, Portuguese, Portuguese  Brazilian ,
Romanian, Russian, Serbian Cyrillic, Serbian Latin, Slovak, Spanish, Swedish, Turkish and
Ukranian.
Changelog:
Improved support for Google Chrome v2.
Fixed bug with IE8 cookies.
Added support for Flash Cookies.
Added Tool to manage System Restore Files  XP and Vista only .
Added support to remove Opera Recently Typed URLs.
Fixed bug which was displaying wrong Total Bytes removed.
Improved exception handling.
Fixed virtual function bug.
Minor performance improvements.