Yes there are publishers out there who accept writers without an agent. It isn't essential that you have an agent, although most will agree it is more useful to have one, than to not. You can do a search on the publisher's websites to see if they accept unsolicited MS.
If you do fancy an agent to represent you and your novel two sites come to mind:
www.agentquery.com and also
www.querytracker.net
Also check out the
Ask the Agent forum for help with agents and such. We have
Nathan Bransford, who is our resident agent, and
Jennifer Laughran as a guest agent answering agent related questions at the moment.