Wacom Graphire 4 4x5. I'd like the next model up (Intuos) for the tilt sensing which would allow for some nice effects in programs like Painter, but I can't really justify the cost. I can't draw for crap, so it'd be wasted. For what I use it for, I'd say I'm pretty happy with the one I got.
Speaking of programs, I forgot to mention I did my coloring in Open Canvas 1.1 (the free version).