I found these in Writer's Digest Guide Presents: Writing & Selling your First Book, which came out in November 2003. For details about these places, see the magazine. All of these publish first-time authors, often unagented, and most accept simultaneous submissions.
In general, I looked through the list for places that were looking for mainstream/contemporary fiction. Although I have romance and mystery themes, I would have to rework my novel to sell to those markets.
1. Barbour Publishing
2. Thorndike Press - May have to make the romance theme more important. Check what they mean by "women's fiction".
3. Down East Books
4. The Invisible College Press
5. Oak Tree Press
7. Union Square Publishing
8. Stillwater Publishing Company
9. Third World Press?
10. Bethany House Publishers - If still following "new" interest in contemporary fiction.