Once we've had them in the tank for a while, I plan to get more swordtails, and a couple of gourami. I'd also like to get a few more neon tetras. And once algae has established itself, we're going to get a couple of algae eaters.
Right now the tank looks pretty pathetic with just those few fish in it.
I also got a blue betta fish, and it's own tiny hex tank for it. I'll probably put him in with the large tank somewhere down the line. I'm not sure if there's a current in the tank right now, and I wouldn't want to subject him to that if it has one.