One of my room mates had two pets mice in college and boy did they stink! it seemed like no matter how often she cleaned the cage, they still stunk up the whole apartment!
Gerbils are nice pets and they don't really stink. My brother wants a pet and I keep trying to get him to buy gerbils. They are pretty low maintenance as far as pets go, and you can still hold them and play with them.
Even rats stink less than mice! But if smells bother you, I would probably steer clear of small rodents.
I have kept and raised rats, mice, guinea pigs, hamsters - I agree with Lauren "Mice stink". Regardless of how frequently you clean them mice have a strong odor. For me the most intelligent and inquisitive of the four species were rats.