What should I get next for this gigantic cage?

I'm making a desk/cage. The dimensions are 5 feet long, 2 feet wide, and 3 1/2 feet tall. It's going to be epic!

Anyways, what should I put in it? I want something that I can't really do on a normal bases, because you need a big cage. I don't want any big snakes, like boas or large python species.

I was considering perhaps doing a multi-species tank. Any ideas?

Thanks!

Hmm.. skinks? do you like lizards?
Emerald tree monitor?
If you want multi-species maybe different colourful geckos?;)