nassarius snails, cerith snails, fighting conch, queen conch, etc, jsut stay away from the sand sifting stars/cukes as they will move sand but will chow all of the animals in the sand at the same time!
good luck
jon
Gobies--do a check on which are more beneficial to have though. You need your LR to be very stable, as they burrow underneath. Just an observation from what I have read here, no experience. A bump for more info for ya........
We've got a pistol shrimp and orange diamond goby combo (they are buds) in our reef tank.
They do a pretty good job at stirring the sand, and the above poster is right, you DEFINITELY need to have stable live rock. Our pair dig under the rock and live there.