Tara, how many watts of light does the tank get? Are you prepared to add fertilizer once or twice a week? Those are the main factors when considering what kind of plants to get.
In my 5.5 gallon I have Anubias Nana, Anubias Barteri, green cabomba, wendtii crypt, brazilian pennywort, Valisneria spiralis (spiral vals), dwarf hair grass and a moss ball.
Here is Zeus' tank with all of that.:
I have a 10w compact flourescent bulb in an architechts desk lamp over the tank and fertilize twice a week with my water changes.