I'm at work, and it's blocking "casino" sites but google this [1] for a start:

"Roulette - Biased Wheels and Wheelhead Speed - Casino News Daily"

I read the cached version, its an advisory for casinos about how to look out for biased wheels. I'll look again tonight when I get home.

well I attempted to look, but there's too many pages for snake oil "beat the house" systems. I may have been wrong since I cannot find evidence, but if a wheel were biased, people would eventually detect it and exploit it. So at the very least, they would analyze the money drops and see an abnormal money flowing out of one particular table.