For the longest time, I had been using two cheap white ones from Ikea or Target (one large, one small). But they are starting to look permanently stained, which is grossing me out, even though I run them in the dishwasher often.
My mom bought me a recycled plastic one for Christmas (http://www.amazon.com/Architec-EcoSmart ... B002C1AVHM
) that is pretty great. It is supposed to be dishwasher-safe, but I think mine warped in ours, so now I hand-wash it. It works best with a towel (wet or dry) under it (but all cutting boards do!).