I'm partial to the watchman gobies, supposedly they can pair up with pistol shrimp, but mine hasnt. My pink spotted watchman actually comes to my tirkey baster I use to feed and takes food out before I can squirt it. He's quite a character.
For blennies I have a lawnmower, excellent algae eater but you need tohave some algae or you have to supplement his feeding. Mine happens to eat everything I put in the tank including carnivourous foods. lol. he's quite the fat ole blenny. But a midas blenny is really nice too, I plan on adding one soon.