I found this while looking for a teardown of a Wii Nunchuck remote since they're cheap and include a 3 axis accelerometer. I mentioned an interface board the other day, but the responsiveness of the interface in this video grabbed my attention. If you like it, you should check out this [via] Nunchuck Arduino RF controlled robot. You can find details on that bot here. The accelerometer itself only runs about $10, but it's a pretty small SMD part.
http://www.societyofrobots.com/robotforum/index.php?topic=2633.0
http://www.societyofrobots.com/robotforum/index.php?topic=2633.0