Unless theyre a root plant (like swords), I usually just put liquid fertilizers in there and have my lights (CFL 6500K) and everything's happy :)
That's actually a 5 gallon!
All of the plants in this: http://www.bettafish.com/showthread.php?t=67565
are good for smaller tanks, so long as theyre pruned. If you can get stem plants to grow a lot, you can even sell them or give them away, which is what I did.
The only one that might be meh in a smaller tank would be the amazon sword, which can get HUGE (tank-busters), but if you have bigger sized tanks to transfer, theyre nice.
Also, banana plants are hysterical and stupidly cute. Theyre cheap, too! (which is never a bad thing ;D )