[flamingo]

If your doing a 10 gallon for bumblebee gobies:

Raise the sg up to about 1.005. Although a few subspecies, etc. are commonly traded, a low "ish" brackish level usually suits most well.
Sand is usually the best substrate, but gravel can also be used.
If your willing to plant the tank, i'd suggest most species of vallisneria, java moss, java fern, cabomba, few types of aponogetons, etc. Java moss would help out with breeding, and java fern would be a good starter plant that they'd eventually "perch" on.
You could probably get away with about 5-8 gobies, really depends on aggression issues. I would really try about 6, with more than that being "cautious". Eventually, they'll form a sort of hierarchy, and may get aggressive to certain others.
Feeding, most bb gobies only accept frozen, or live foods. I've had some take flake food, but it's really rare to say the least. Chopped up worms, gammarus (scuds), nematodes, frozen and live bloodworms, frozen squid, live and frozen adult brine (live being gut-loaded), frozen mysis shrimp, etc. are all usually accepted. In the end, they're favorite food seems to be live blackworms, although it's expensive and usually hard to find.
Are you going to try breeding? If so, provide enough rock ledges, and empty pond snail shells. If parameters are met, and they're fed good enough, they'll usually pair up and lay eggs inside of the shells, under plants, etc. I've heard of a few people going through with this, but fry are very small and require a lot of work.

Need anything else?