Planted Tank Enthusiast
Join Date: Aug 2007
Location: Catonsville, Maryland USA
I have grown or am currently growing these plants in a 2.5 gallon:
Anubias nana "petite"
Pogostemon helferi ("downoi")
This is by no means an exhaustive list; if you browse the forums for awhile, I'm sure you'll get some other good ideas.
With the level of light you're using, I think you'll want to do co2, or at least Excel.
Instead of medium gravel, I think something smaller would look better in such a small tank.