I agree. I have used this method many times with colubrids and fast moving lizards and it usually works like a charm. Its also serves to get the animal (especially snakes) into a nice, compact pose so that you can get the entire body in the shot. Here a few pics that would have been impossible for me without the help of a water bowl:
Another thing that I think helps is to bring the animal's cage over to your photo setup and transfer the animal right from its cage to the background, disturbing it as little as possible. I find that the more you handle them prior to setting them down, the more active and problematic they become.
Good luck!
Aaron