Well generally it's colours that compliment each other. Blue is regarded as the most official colour for a business website (did you know that?)...
I've also seen it said that you should use no more than 3 colours for any given webpage (plus white and black).
Anyway, here's a colour picker that prompts you with some co-ordinating colours...
http://www.wellstyled.com/tools/colo.../index-en.html
use the different buttons to adjust - Contrast, Pastel, Pale, etc etc