A tiny program that puts an icon in the right side of your menu bar. Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers. Click it again to go back. Hold down the Command key while clicking to show the menu.
Ben pointed me at this one. I can’t count the number of times I’ve wanted to override my defaults for screen timeouts, and now I can!
Everyone needs Caffeine. And they really do, because every time I see someone's screen sleep during a presentation, I think, "everyone needs Caffeine".