Poets and Writers magazine have developed The Literary Agents database. It includes agents who represent poetry, fiction, and creative nonfiction, plus details about the kind of books they're interested in representing, their clients, and the best way to contact them. Click on the title of this post to go straight there.
Meanwhile here's an example of the kind of information they provide.
The Steinberg Agency
47 East 19th Street
New York, New York 10003
Accepts E-mail Queries?
Interested in Representing:
Autobiography/Memoir, Commercial Fiction, Historical, Humor, Narrative Nonfiction, and Pop Culture