1) Corydorus Panda - My third cory variety and the tightest schooling I've ever seen, they often do syncronized glass running, its fun to watch!
2) Penguin Tetras - Kind of surprised me, but even in a ten, these guys tend to at least hang out in a clump when the light is on, when the light's off they dive for high cover (I use a fake plant minus the base that floats).
3) Cardinals - One of my LFS's had a large planted tank with these guys in it, it was lovely.