What Can We Do with the Placenta?

My wife is 8 months pregnant. We've done a lot of reading, taken childbirth and parenting classes, and we thought we were ready for anything. Then just the other day, a friend asked what we were planning to do with the baby's placenta. Frankly, the question had never even occurred to me or my wife. But now that we're thinking about it, it seems strange to just throw it out. Do you have any suggestions?