Screensaver module executes an AppleScript of your choice.
ScriptSaver is a Mac OS X screen saver which executes AppleScripts when it is activated and/or deactivated. For example, ScriptSaver can pause iTunes when the screensaver is activated, then unpause it when you return to the computer. It's limited only by what AppleScripts you write!
What's new in ScriptSaver
The desktop can be shown while the activation or deactivation script runs -- so you can display dialogs and messages to the user
The desktop can be shown in place of a screensaver (the "None" option now leaves the screensaver transparent)
Deactivation scripts are less flaky -- they can be launched synchronously so that Mac OS X doesn't terminate them prematurely
The iTunes Visualizer can be used in place of a screensaver