I just put my first small tool on GitHub: forbidSleepingMode. It will forbid your (Windows) computer to enter into sleep mode, acting as if there was activity all the time. I’m sure you can think of 1001 productive uses for such tool.
Technically, it just sends a “tickle” to the computer every 10 minutes forcing the display to remain on (hence: don’t set your screensaver to come before 10 minutes). Build it with Visual Studio 10 (I know, I know …).
The mandatory screenshot (very, very useful):