Need some ideas...

Inverts, fully aquatic turtles/frogs, you could probably do plecos for weeks, small oddballs such as african butterfly fish, oddballs in general... There is a lot, it depends on how you want to categorize. If you go into marine I imagine you wouldn't have any trouble at all.

It might seem a bit unnecessary or silly, but I thought it could be interesting to share some of the rarer fish from Jeff Rapps, Wes, Jojo and other vendors. A lot of them are displayed as a scientific name and not much picture wise. Not like care sheets but maybe a short description and pictures. It would share a lot of interesting fish you won't see in an LFS, and give them an opportunity to pick the fish up if they are interested. It's just a thought though.