Check some of the frozen stuff from Hikari, SF Bay, etc. They usually have some kind of frozen cube thing which has a bunch of different things in there.
SF Bay has something called Marine Cuisine. It has spirulina in it, krill, artemia, mysis, and other stuff. That stuff you can give to your corals.
You can also mix or make your own food too. melevsreef.com I think thats correct has something about making your own food for your tank.