For blender users, there is an edge finder called freestyle that does some interesting kind of hand drawn looks. This is something I had on my hard drive I did a while back that I did with it:
You have to download the entire blender program to try it out or else recompile it yourself. Keep in mind I just played around with it for a little while and it's a very large image. A smaller one would look better I think. Also, there are lots of other scripts for different effects.