After reading the article Contrast is king at A List Apart, I checked out one of the tools that was mentioned: CheckMyColours.com. It's pretty nifty and will help you deal with your sites accessibility. Got any other nice tools for accessibility? Please suggest one or two in the comments!
It is a tool for checking foreground and background colour combinations of all DOM elements and determining if they provide sufficient contrast when viewed by someone having colour deficits.
All the tests are based on the algorithms suggested by the World Wide Web Consortium (W3C).