I'd say a really cool looking betta, a small school of tetras, and an otto or maybe some cories. I'm thinking about doing the same thing with my 10 gallon as soon as its done with its crazy cycle.
Maybe otos and gohst shrimp, but they do best in a species tank so I would advise against putting anything else in the tank with them.
Some fish that would do good in your tank (google image search them for pics, then tell us wich ones you like, then we can tell you wich you can have with what other fish and how many), not every fish that would do good in your tank but some of them:
neon tetra
black neon tetra
serpae tetra
lemon tetra
black phantom tetra
Red phantom tetra
smaller danios (no giant danios)
any rasbora species
otos
most corydoras species (I suggest you avoid larger species like bronze corys)
betta (male or female(s))
paradise fish
male guppies
male platys
heteranda formosa/drawf livebearer
honey gourami
shell dwellers
most killifish species
Remember, I'm not saying you can have all of them in the same tank, just giving you ideas.
Ottos in a species only tank? Really?? I mean ghost shrimp in a species only tank I can understand, everything eats ghost shrimp. But what fish that would live happily in a 10 gallon would want to eat an otto? Or even catch one for that matter lol.
I had an otto in a 10 gallon with dwarf puffers and they did fine. Actually, that otto was my favorite fish. He survived a VERY long time, even after I temporarily shut my tank down due to an illness in the family. I actually thought that the otto had been eaten by my cat or something because I couldn't find him anywhere, but when I began to clean my tank out he was still in there just as happy as he could be. I could hardly believe it! Sadly he didn't make it after getting used to living in the stagnant tank water for 8 months, he couldn't handle the clean water.