I know you said you're not big on insects, but what about some type of rare praying mantis? i've seen some pretty interesting species for sale over here which all seem to stay really small, so that would almost definitely work in a cage that size?
Otherwise, might be an idea to list some of the things you definitely DO NOT want to keep to narrow down the field...
-EDIT-
Or maybe something like a Pygmy Chameleon might work? although possibly more effort required?
Do u have pics of a Pygmy chameleon? That sounds awesome. What is a 'rare' praying mantis? I have actually never seen a mantis close up in person or in pics online. I might have no idea what I'm talking about.
