Welcome to Gaia! ::

Does self-publishing count? If so, I did it with Lulu, publishing a short book I wrote yonks ago.

Anyway, enough about me...

As for agents, I've been collecting links on my favourites bar, but since I'm a UK resident, I've kept on the lookout for UK-based agents, although I think I do have the link of a US agent because she represents a writer I greatly respect.
I don't have any publishers links right now, because I think it's best to get an agent first, then a publisher (and I know editors come into the equation, but I'm not sure at which stage, yet.)

http://www.aitkenalexander.co.uk/submissions.php
http://www.writershouse.com/content/submissions.asp
http://www.davidhigham.co.uk/

That's all I have for agents, but I do have some good agent-related information links.

http://hollylisle.com/fm/Articles/agent3.html#russ
http://hollylisle.com/fm/Articles/agent2.html

Hope that helped!

Oh - the editor bit. Editors come in once you've decided you've done as much work as you can on a manuscript, and are toying with the idea of sending it in. Then you, regrettably, shell out money (or, if you know an editor, flattery, baked goods, and flowers) to have them make it better. Yeah, it sucks paying money. But it will be much, much better, and much more likely to get accepted. A lot of publishing houses aren't accepting unedited manuscripts anymore, and some of those that are are turning down unedited manuscripts anyway, because they don't want to pay their own editor any more than a copy-edit.