Just so you know, I think you're a great parent to get your daughter fish. My parents got me an aquarium (or rather several through the years) when I was young, and I still remember playing with my fish as some of my favourite childhood memories (next to my dog, but dogs are different).
You might consider a betta, sometimes known as a Siamese Fighting Fish. A male betta is usually popular with kids, since they are a little hardier than other fish, don't have high aeration or filtration needs, and have some fun, stimulatable behavior (not to mention you can get one for less than $3 at the LFS
). One of my favourite memories from childhood is putting a mirror up to the betta bowl and seeing Peaches (as my 6-year-old self named the poor guy) flare up and attack his reflection.
A betta is also easy enough to take care of you could even have your daughter partly or even mainly in charge of its care. Teaches responsibility and all that jazz. Something that's a viable option for a 10 gallon is to buy a see-through tank divider, divide the tank in half, and put a betta in each half. This lets you get two different coloured bettas (and they come in a lot of colours) and see how they interact with each other. Good times all around.
Good luck with whatever you get for your daughter!