rosy boas, scorps, pac man frog, tarantula, Whites tree frog (AKA dumpy frog), anoles, hissing cockroachs, lots of diff type frog set ups.
If you want to sell your kidney you could get an anthill python, they are supposed to be REALLY tiny, like getting up to 3ft max or something, but I could be wrong.
You could also use it for a baby tort set up, since they grow so slow (don't quote me on that! lol) a 20 gal long would be fine for a while. So you would have enough time to build a bigger cage.
Neptune, Zion, Enigma,