Smart Bomb PC Shutdown is a power-off utility with intelligence. Aside from being able to turn off your machine after a period of time, it can monitor CPU usage and Internet activity in order to delay shutdown while any processes in that regard are going on. It will allow you to run any multimedia applications or download files while you are away, knowing that the computer will be turned off when all processes go idle and not earlier.
More info:
hxxp://www.moon1000.com/software/products/dabomb.shtml

I'm going there right now :lol: