Update: the ramshorn's doing an awesome job on the algae (although he looks like the swamp thing because he can't clean off his own shell, of course), but he poops. A LOT. So there's a lot more water changing. On the upside, my betta doesn't mind him and he's a lot of fun to watch.
In the 3 gal Eclipse, the two dwarf Ras Hets, two glowlight neons, and one ghost shrimp have formed a very happy little community (we call them the Syndicate) - everyone gets along, no problem, and weekly 25% water changes are keeping the chemistry in balance. They're currently in residence in the kitchen - well away from heat and chemicals, of course - and they seem to love being where the action is.