Hamsters, believe it or not, can eat meat. They enjoy chicken (cooked, unseasoned) as a treat, and tiny amounts of hams (although I don't like feeding them ham). They also LOVE mealworms, another m, apart from Munchkin who is one odd little hamster o.o. So as a very rare treat, feeding your hams a little chicken is a good idea. It is packed full of protein, which i s why it is often suggested for pregnant hamsters, and makes a tasty little titbit.
Don't feed them beef! That is pretty much the only mainstream meat I would say avoid. The rest are fine in small amounts(and most LOVE mealworms!)