Hard Boiled Books has posted an anthology call for "Gumshoe Mysteries". They're looking for stories of 2000 to 10,000 words in the hard boiled mystery genre which includes murder mysteries, private eye stories, and police detectives or federal investigators. The deadline is October 1. You can find the details here. This is a non-paying market. They also run monthly flash fiction contests. The picture for this month's contest is on their home page.
Thanks to Michael Bracken for the tip!