Lingon – GUI configuration of launchd
Sure, Lingon may have one of the ugliest and more boring icons in Mac OS X (apparently the red blob is supposed to resemble a berry), but we can all easily overlook the icon when we see how useful this app really is. Lingon provides a much appreciated GUI to configure the launchd system daemon, which allows you to set schedules for applications and scripts to run. There’s plenty of room for error however, so it would be a good idea to familiarize yourself with how launchd works before you start altering anything major.
Here’s an explanation from Apple of launchd:
In Mac OS X v10.4 Tiger, Apple introduced a new system startup program called launchd. The launchd daemon takes over many tasks from cron, xinetd, mach_init, and init, which are UNIX programs that traditionally have handled system initialization, called systems scripts, run startup items, and generally prepared the system for the user. And they still exist on Mac OS X Tiger, but launchd has superseded them in many instances. These venerable programs are widely used by system administrators, open source developers, managers of web services, even consumers who want to use cron to manage iCal scheduling, and they can still be called with launchd.