Following the good advice from Christian Pearce, I downloaded ArtRage tonight and decided to try it out. I haven't painted in ages (weeks Digitally and years Traditionally) so it is a little painful but it was real fun!
I'm on the demo version (hence the beautiful duck-poo color watermark). I'll try some more tools and drawings in the next 29 days to make up my mind, but I am already seriously thinking of buying it. Yep, it's that fun, you should give it a try!