Josh Siegel brings you animal art every Monday. Add your own requests in the comments, and maybe Josh will draw an animal for you.
For rollsnideroll, "I would like to see sloths doing aerobics." I think this is the second idea of rollsnideroll's that I've used, and while I'd generally like to avoid repeats, it's impossible to argue with sloth exercise.
Check out more of Josh's drawings on his Tumblr.