I just adopted my boy, Ringo. The rescue said he was an Australian Shepherd mix. What do you think?
http://s1303.photobucket.com/user/4-Amigos/slideshow/Ringo
http://s1303.photobucket.com/user/4-Amigos/slideshow/Ringo
So many people guessing American Bulldog!!! I don't see that! The Am Bulls I've known have had less smushed faces than his so I would assume boxer or a smaller bulldog type dog, especially since he's likely mixed with something less brachy.
I also think he would probably be bigger. Genetics can be cray, but I don't think an AB cross is likely to give a 30-50# mix unless the other half was teensy.