There's also the Yinova (I think I spelled that wrong) that goes for cheaper than the Cintiq, though I was talking with some dudes last night with some experience with it and they said it reacts to your cell phone signal....
One of my friends from school got the Yinova 22"HD for Christmas and seems to be loving it.
I work smaller, so 22" would have been way too big for me. Maybe one day!