Try petfinders, there's lots of cute mixed breeds there!
Be aware that many people charge a lot of money for cute little mixed breed dogs, telling buyers they are some sort of special breed. A Schnoodle is just a fancy name for a Poodle bred to a Schnauzer - both of these dogs have their own genetic health problems, and someone "breeding" them on purpose is unethical and therefore won't have done any health clearances on the dogs.
Here's an article on the fad of selling "mutts."
http://www.netpets.com/dogs/newsroom/crossbreeds1.html