Yeah, make it at least 4' x 4' x 4'.

Toads are boring? Blasphemy! In my book, toads are third in the hierarchy of frogs. First is treefrogs, then darts/mantellas, then toads, and finally Microhylids. Bullfrogs never even make my list. Some of my favorite toads are Melanophryniscus stelzneri, Ollotis alvaria, and Anaxyrus debilis. See John's albums for pictures.