what kinds of fish can live with beta?

We Currently have a small 3 gallon tank in the bedroom with A Beta who is living with several gupies. There was very little nipping of the fins. There is also a small dwarf frog that lives in the tank and has done very well. The frog eats the bloodworms and the other fish leave him alone to roam the tank. The Beta is deffinetly the master of the tank. I would have to assume that as long as the other fish in the tank are much smaller then he is and not aggresive they should be ok. But remeber that on general the smaller fish are going to be schooling fish and should be kept in groups of 5 or more. And for some reason, odd numbers do the best.