Well, the frogs that carry tadpoles on their backs aren't live-bearers. They are mostly dart frogs like Oophaga pumilio and mantellas like Mantella laevigata. This by no means is a complete list of frogs that exhibit this behavior.

There are pictures of both species in one of John's albums, not to mention the climbing mantella article, and the pictures Alex Shepeck posted from his trip to Costa Rica.