OnyX is a multifunction utility for Mac OS X. It allows you to verify the Startup Disk and the structure of its System files, to run miscellaneous tasks of system maintenance, to configure the hidden parameters of the Finder, Dock and of some of Apples own applications, to delete caches, to remove a certain number of files and folders that may become cumbersome and more.
Whats New:

Version 2.2.8b1:

Deleting Browsers History improved
Maintenance and Automation panels improved
New Info > Memory panel
Purging the inactive memory
Enable/disable virtual memory swapping
Some cosmetic changes

Requirements:

Intel, Mac OS X 10.6 or later