I've mentioned Penumbra here before but of special interest to crime writers is the upcoming Alfred Hitchcock issue. The reading period for this one begins on May 1 and runs through July 31. They're looking for shorts up to 3500 words of Hitchcock with a spec fiction twist. Payment is 5cents a word. You can find all the details and other themes and reading periods here.
Hat tip to darkmarkets.com
UPDATE: May 14. 2013 Please read this post before submitting.