I haven't heard of one. Didn't think you could even make very complicated (or even good for that matter) beats on a mobile device but I could be wrong.
Posted from my CrackBerry at wapforums.crackberry.com
I would love to have a beat maker for my phone. I know the iphone has a few applications that do this and I know top producers are even making full tracks on them. I would pay for a good beat application for the storm