ThylacineAlive- I haven't heard anything about the permanent tortoises in a while, so I wouldn't go around posting saying that they are really interested in getting them. Rainforest Reptiles is an orginization that specializes in herps. Their stay at the zoo in August included a trailer with herps that unfortunately had many mediocre exhibits, and a show. Beardsley typically has a temporary summer show each year, though I'm not sure if this counts as a temp exhibit.
Maritime Aquarium relies a lot on temporary exhibits. For a while, they temporarily had African Penguins, and for the first time in a while, they had White Alligator on display in 2012. Their Meerkat exhibit right now is temporary, but might end sometime soon. It is unsure when it will end as they are immensely popular.
Mystic Aquarium has a seasonal Birds of the Outback aviary with Cockatiels, Budgerigars, and Eastern Rosellas.
Busch Gardens Tampa replace their Asian Small-Clawed Otters for a little bit with penguins, as part of their Christmas Town celebration.
Isn't the Arctic/Antarctic exhibit at Aquarium of the Pacific temporary?