Coffeebean

Coffeebean sits in your Mac's menubar and lets you temporarily disable automatic sleep, dimming, or your screensaver for however long you want. If you're working on battery or have efficient power settings and you need to leave the screen on, just click the little coffee cup icon and activate Coffeebean. It's small and unobtrusive--Coffeebean stays out of the way and keeps the lights on when you want it!