I know people have mentioned E-Reads in this thread, but have you checked out their site? They have a Mystery category:
http://ereads.com/ecms/genre.php?cat=14
And a suspense category:
http://ereads.com/ecms/genre.php?cat=19
Unlike Baen, they don't publish new books as far as I know. The E-Reads titles are all previously published books that came out in print first, sometimes quite recently, some years ago. For example, they have everything from cozy mysteries by Jacqueline Girdner to the early Destroyer novels.
Also, Belgrave House started out reprinting out-of-print Regency romances, but they have some mysteries as well, including historical mysteries:
http://www.belgravehouse.com/booksto...okjtmcs6d2rro0
I liked Lora Roberts' Murder in a Nice Neighborhood, by the way. I read it when it first came out in paperback.

The heroine is unusual because she is essentially homeless, a freelance author living out of an old VW bus.
Like Baen, both publishers put out DRM-free editions in multiple formats.
Now we need more print publishers putting out affordable non-DRM e-book editions of new books.