I like the idea of mixing the hash symbol with a b. I'm not a good digital artist, but check this out:


If you can't see the hash, I highlighted it in this one:


It's very easy to write, and looks good. Just draw a 3 and 2 lines through the top. I got the idea from this post: http://forum.bitcoin.org/index.php?topic=25102.msg325489#msg325489