I've been curious about a B:ass Master myself. The Brass Master patch on my Pod is fun to play with, but not really usable for either of my projects, so I think it would be a waste of my money at this point to buy one.
Also on my Pod, I've had a lot of fun with the Boss Metal Zone patch (It's called Killer Z or something). Pull that up, and as long as I'm the only one there, it feels like I'm channeling Burton. If someone is there... well... I just feel like a jerk with way too much distortion.