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!

Internet Explorer
Temporary files, URL history, cookies, Autocomplete form history, index.dat.
Firefox
Temporary files, URL history, cookies, download history.
Opera
Temporary files, URL history, cookies.
Windows
Recycle Bin, Recent Documents, Temporary files and Log files.