Look at the Reef Packages on this site. They give you decent recommendations for inverts for your size of tank. Most go with hermits, variety of snails, emarald crabs, sally lightfoot, shrimp, and maybe a sand shifter cucumber. Just don't make the mistake I made and get a good selection of inverts in your tank, then put a fish in that loves to eat them (puffers, wrasees, etc.).