MacJanitor
MacJanitor is designed to be used on a periodic basis by Mac OS X users who don't leave their computer on (and awake) 24 hours a day. If you've been leaving your machine off at night without allowing the maintenance tasks to run for several weeks or more, the first time you run them using MacJanitor may take several minutes. Also, if your log files have grown extremely large and you are low on disk space, the tasks may have problems moving the files around and compressing them. After that, it typically takes less than a minute for each task.

Onyx
OnyX is a maintenance, optimization, and personalization utility for Mac OS X (PowerPC and Intel). It also makes it possible to configure certain hidden parameters of the Finder, Dock, and Safari, to remove a certain number of files and folders that may become cumbersome, preview the different logs and CrashReporter reports, and more.

Commercial

Cocktail
Cocktail is a general purpose utility for Mac OS X. The application serves up a scrumptious mix of maintenance tools and interface tweaks, all accessible via a comprehensive graphical interface and toolset. It is a smooth and powerful utility that simplifies the use of advanced UNIX functions.

All latest versions of Cocktail are available as free updates for registered users. When unregistered, Cocktail runs in demo mode and will expire after the tenth launch.