Alright, I've sold out and obtained a Twitter (follow me! Lynne Schmidt :) ). And it turns out, it's much more fun than I thought it'd be....
Social networking is huge in the literary industry. It's why we have conferences, and book signings, and book clubs, and critique groups (the list goes on).
You can find many agents on Twitter, or some have Facebook pages or even blogs. It's amazing how open and honest and HELPFUL these people are. They'll tell you what they're looking for, what they're NOT looking for, what they'd LOVE to see. Some more insightful blog posts have actually explained to me why and how manuscripts are chosen. Some agents (See FinePrint Literary) even go out of their way to critque your pages for you, or even your query letter (have you heard of QueryShark?). Some give feedback, some are WAYY too busy. But in reality, all agents do the best job that they are able to do, and as a writer, that's something for us to keep in mind. Don't be offended by form letters, rejoyce in rejections that give reasons why you're rejected.
Moral of the story is: if you're trying to get published and you're not doing your research, you should be. There is a lot out there that can help.