Is this a reef (what kind?) or FO / FOWLR?
Damsels can be aggressive, more so in smaller tanks. You'll want to keep an eye on him.
Royal gramma, unless any of your shrimp are super small. Black cap basslet - same thing.
Fairy or flasher wrasse.
Dwarf angel (not necessarily reef safe).
Blenny of some sort.
Various gobies - I personally love neon blue gobies, and they get along with most other gobies as well.
Cardinals.
Probably many more - check out liveaquaria.com as they have a good listing of fish, along with recommended tank sizes and other requirements.