Is this showcase for fantasy or science fiction? In either case, for orcs, you'll want to go beyond tabletop and add all sorts of orky bling. Skulls, corpses. Snotlings, orclings, and those round head things with teeth come to mind as "pets" that I've often seen on bases. You can also consider partially painting the miniature, fixing it to the base, then painting the miniature and base together as cohesive artwork. Also consider making a pseudo-diorama, where, when you put all the miniatures on their movement tray, you have a mini-diorama with its own scene (eg. a bunch of orcs on a rock outcropping).
Guh. Now I gotta do this with my stupid orcs.