What does a literary agent do, exactly? Don't be ashamed if you're still a little unclear on the subject. I'm not always totally clear, and I have an agent! The helpful people at Dystel & Goderich explain further the agent's goals, from the agent's point of view:

A couple of weeks ago, a woman came to me for representation. She had been offered a publishing contract by a small academic publisher who had sent her their contract. When the woman saw the contract, she felt many of its terms were unfair and she went to a friend of hers to ask if she should get an agent. The friend advised that "the purpose of an agent is to bring buyers and sellers together. Once a seller has a buyer, then the agent's job is basically done."

Frankly I was stunned, to say nothing of very annoyed. We are not in the real estate business - which is what this person, who happened to be a published author - had made it sound like. In fact, we do a great deal for our clients in addition to selling their books, and, as the business has changed over the years, we seem to be taking on more and more of what the publisher used to do.

Elaboration here.