Personally, I'd go with one or two crested geckos. They are adorable, are not difficult to care for/feed, and have great little personalities. I wouldn't do more than 2 in that size and others with more experience might only recommend one. But even one would be a nice display if you do up the enclosure as a natural rainforest vivarium....

Incidentally, you can find lots of gecko supplies, including the Repashy diet, at Pangea Reptile.