OnyX

It allows you to run misc tasks of system maintenance, to configure some hidden parameters of the Finder, Dock, Dashboard, Exposé, Safari, Login window and of some of Apple’s own applications, to delete caches, to remove a certain number of files and folders that may become cumbersome, to see the detailed info of your configuration, to preview various logs and CrashReporter-reports, to check the Preferences files and more. Link