I agree with Playtime. They ARE easy to feed, however they do not eat much when there is competition that is bigger than they are (most fish) and/or more assertive at feeding time (most fish!) Also many species of Goby have unique "niches" in the wild that should be replicated as closely as possible. While this is often not difficult, it may not "fit" with the scheme of the tank. Many species share a symbiotic relationship with the Pistol Shrimp(s) that can be cool when duplicated in the tank.
Decide what part of the ocean your tank represents, and go from there. As the Gobies represent the largest Family of fishes with regards to # of species, there's probably a Goby or 2 (or 3 or...) that will be happy there.
KNOW YOUR GOBIES!!! Baensch Marine Atlas (V1) has a comprehensive section on the Gobiidae.
Playtimes right, Mandarinfish are dragonets, as is the Scooter "Blenny." Maybe we can offer some suggestions as to species if you let us know more about your tank/goals.
Regards,
YBYW.