Cocktail is free general purpose utility for Mac OS X 10.2 or later. The application simplifies the use of advanced UNIX functions and gives access to hidden Mac OS X settings.
– update prebinding information
– run cron scripts
– repair permissions
– delete locked or unaccessible items
– enable and disable journaling
– delete archived log files
– create symbolic links
– view log files
– change network card setting
– request new lease from DHCP server
– force empty trash
– recreate alias to Mac OS 9 desktop
– remove cache files
– customize look and features of Finder and Dock
– easily opitimize your system using Auto Pilot.
It’s freeware, 1.4MB, and requires Mac OS X 10.1 or later. More info here.