I was told once that it is a good idea to have your lights in a room on a different circuit breaker than your wall outlets. Their reasoning was that if you needed to work on something in that room, you could turn off one circuit and still have access to a power source (for tools or lights ect...). I thought about this for the house I'm building right now, but decided it wasn't worth the trouble for me because I own enough cordless tools that it should not be a problem.
Waldo