Kinetic Development has made a rather sweet M-Lok QD rail called Kinect. They are spring loaded to lock onto the M-Lok holes. There is a release button that you push to quick detach the Kinect mount from the M-Lok handguard.
Kinect rails/mounts are available on their website. At the moment just the 4 slot and the bipod adapter are available. The rail is $49.99 and the bipod adapter is $59.99