Regarding your question, "how do I find good color schemes?", here are two web sites I found useful in the past:

http://colorschemedesigner.com/

http://www.colourlovers.com/

Poking around Color Scheme Designer should also answer your question "is there a formula?" -- the answer is yes, there is (bad taste notwithstanding).

See also http://en.wikipedia.org/wiki/Color_theory and this old comment of mine: http://news.ycombinator.com/item?id=2130084

EDIT: this page, linked from the Wikipedia article, is also quite informative: http://www.worqx.com/color/