Shutter is a customizable program that lets you perform a variety of actions when a user-specified event occurs. Events include timer countdown, a certain time trigger, low CPU usage, user inactivity, a low battery etc. The corresponding actions include shutdown, reboot, logoff, lock workstation, sleep, hibernate etc.
The program can play a custom sound and/or run a program of your choice, in addition to displaying a user-configurable message. A web interface is also available that permits remote execution of one of a list of actions.
Note: A pro version is available without the limitation of 5 presets, events and actions.