I suggest a shrimp tank, lots of fun to look at. Put some hearty lower light plants like java fern, anubias, and/or an interesting moss like a flame moss or willow moss and a nice piece of driftwood. You avoid some of the algae issues that come with running higher intensity lights and can run all of those off some quite small leds. Add a nerite snail (they cannot breed in FW, so no snail bloom) to help with clean up. If you like some fish to watch, the small galaxy rasbora (aka celestial pearl danio) are a beautiful small fish, and they don't interfere with the shrimp. Just my 2 cents.
- Ian