Gimborn Beef Liver Freeze Dried Training Treat for Dogs
http://www.carealotpets.com/item-det...00000000001226
We break them up into smaller pieces, then we put them in a tin, & keep it by the back door. When I want Sammy to "come" or reward him for going potty, I just shake the tin (he knows the sound) & he comes running. We don't give him a treat every single time. We keep him guessing. I would say he gets a treat 80% of the time

You can get these at Petco, Petsmart, Care-A-Lot, maybe other places too. You can definately order online too. Seems kind of expensive, but we have had the same bucket for at least 4 months.
Also he likes Vitakraft Deli Style Treats (Sirloin) also broken up into little pieces.
http://www.carealotpets.com/item-detail/?ItemID=4234E