10 gallon eh? I know, spectacled caiman! .... Reptiles only grow to the size of their tank right?
Seriously, there's tons of cool little lizards and small snakes. I used to have a Mexican Night Lizard in a ten, which is a funky, vicious little thing that reminds me of a tiny tegu.
Moon crabs are little demons LOL, but they are pretty cool. They look a little big for a 10 gal dont ya think? Most people seem to keep them in groups anyway. I dont think theyre aquatic though. You must be thinking of another crab. I saw a table at the NARBC expo with a rubbermaid with about 10 crabs, and all they had was sand and the crabs looked fine.
Sandfish would be a great choice though! Theyre not usually CB, but they are one of the hardiest little lizards when WC.