xscreensaver

Save your screen while you entertain your cat

Xscreensaver will run several programs to continuously update the screen instead of going blank. You can specify the programs and their arguments using resources. You can also add dpms (power saver) options. Xscreensaver will make use of any installed OpenGL libraries, such as Mesa (also in the ports collection). The client-server model employed by xscreensaver make it a superior choice to xlock, since no separate auto-locking program is needed. It's also extremely easy to add new programs like xearth, or any other program that can fill the root window as additional screensavers.