I would have to agree with pk in the fact that nana is about the easiest plant to grow, in low light situations, lilies will do well, also red indian swords will do well in lower light situations, to add a little bit of contrast to the green from the other plants i also find corkscrew vale easy to grow, try those types of plants before spending tons of money on high light, high co2 needing plants.
I just picked up some rotala, narrow leaf red ludwigia, onion plants, and some very tall corkscrew vals for my 18"Wx26"T 30gal. There is also one other plant I forget the name of that I absolutely LOVE. It's a plant not commonly available and ironically as its my favorite, it now looks like its dying. Hopefully it makes a recovery. The moron at the LFS crammed all my plants in one bag including these which have those stems that snap like pretzels. 2 of the clump of 3 luckily didn't get snapped but I bought them without roots and they're not looking too pretty atm. Hoping that will change and also hoping I have enough light.
Maybe if I get the camera batts charged I'll try and get a pic of it. Someone must know what it is.
Something else that requires some high light and Co2 that I'm dying to get is Fissidens Fontanus, or phoenix moss. This crap is freaking great looking in some very nice aquascapes. It's like java moss on steroids, aesthetically speaking. Dwarf Baby Tears are another favorable mention but usually want a little bit of Co2, they'll still grow without it, however.
The only plant I've been able to find online that closely resembles it is something called Limnophila Hippuroides (which I actually kinda like better than what I've got), but the colors are inverted, red top, green bottom, and the stalks grow a bit different. -.-
Also note the tank isn't even close to being a finalized aquascape, its still cycling, the driftwood is being held down by rocks, and I've yet to pick up the PVC pipe I'm gonna use for cave structure, in place of that stupid fake log which the driftwood is hiding.
Edit: Apparently it won't link to the exact album so just click on the 'New Fish Tank' album. duh. lol
Some others that I looked up yetserday and thought were interesting:
Rotalla Walichii
Red Tiger Lotus***
Cardinal Temple