There's an invaluable book called "The Writer's Handbook", which lists publishers and their specialities, plus contact details. I'm only familiar with the British version of course, but Amazon.com lists several similar American publications. Probably not something that you want to buy, but your library might have a copy?

Be wary, though. Looking through the reviews on Amazon.com, it seems that the American version of "The Writer's Handbook" is pretty much just the British version in a slightly different jacket, so it might not be a lot of help to an American writer. There must be a proper American equivalent, though.

ETA: The Writer's Market might be more use to you.