Id say bettas! (Gasp! Bettas CraZ says??)
With females you can have more than one and great friendly group of girls they are!
I havent had a lot of luck with neon-tetras (and so I have heard that others dont have good luck as well), but go for those too if'n ya want! Danios are neat-o, fin-nippers tho, so watch for that...Tho not much you can do about it!
hmmmm what else can i come up with at 3:20am??
(Im so tired Im hyper!) Oh! Maybe a few corys?? They dont take up a ton of room and they are cute! They remind me of little fishy-puppy-dogs!
There are a lot of small fish that could work for you that are pretty too
Like a lot of tetras are small, (except for my 3 HUGE Congo-tetras!) or ummm hmmm maybe Maybe MAYBE a dwarf gourami?? Not sure on that one. May not be suitible for him... dunno! Never hurts to suggest it tho!
I'll go now, Im sure my senseless babble is getting annoying! Good luck with your tank and its future inhabitants!!!!