What kind of pet can i have in....?

a 29 gallon tank filled 1/4 with water. i was building it because i was getting some but then i started thinking about other animals. i dont want lobster or crayfish again. what other cool animals can i have in it. salamanders, frogs, etc, etc. it doesnt have to have water either but no snakes or gerbils or anything. thanks for your ideas, thanks!