I do it more literally than most. I often play my DS and X3: Terran Conflict simultaneously, the game is slow paced, has an autopilot, and you can get your fleet to manage themselves only occasionally requesting your help. I could instead speed up time in the game, but I prefer the leisurely pace.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.