I'm not to versed in the ways of a community tank...as i usually keep my cichlids in tanks to themselves or species tanks. However pending approval of a more qualified poster i'd say some Apistos (cockatoos) and a school of Hatchets will be fine in a 30gal. Of course the hatchets are pending, for sure you can keep apistos in a 30gal.
Like Strait said though, there are other choices. Most of the shell dwellers from Lake Tanganyika, Apistos, Rams, checkerboards, list goes on.