How can I get my book published without an agent?

Avoiding self-publishing is probably a good idea- it looks narcissistic and bad to agents and publishers later on. Get yourself a current copy of The Writer's Market and start looking for publishers that both deal with the type of book you've written (if your book is sci-fi, then it'd be silly to send it to a publisher that deals mostly with historical non-fiction or romance novels) and that accept unsolicited manuscripts/manuscripts from writers who aren't represented by agents. Then start sending out manuscripts. But be prepared for a lot of rejection. Gotta keep a thick skin about it.

Get a copy of Writer's Market and a copy of How to Be Your Own Literary Agent. Follow the advice that they give. There is no guarantee, but that;s the best way to begin.

well, you can send directly to publishers, but your chances of one of them even looking at it are slim to none. They generally don't like unsolicited manuscripts, which is why the best way all around is to do it through an agent.

Can I ask why you don't want to go through an agent?

Go with an agent so you don't get hosed when it becomes a Best Seller and you get cheated out of the lions share.

On the Internet.