I have covered the Mayflower R&C Placards before but I recently found that their sister company, Velocity Systems, has their own line of 4 placards: the MOLLE Placard, the Elastic Placard, the Triple M4 Placard, the and Quad M4 Placard.
The MOLLE Placard is a plain, user-configurable MOLLE panel. The Elastic Placard has 3 low profile elastic M4 magazine pouches. The Triple and Quad M4 Placards hold 3 and 4 M4 magazines respectively and have MOLLE webbing on their front.
Like the Mayflower R&C Placards, these are also designed to bolt to the front of compatible plate carriers via the Swift-Clip system.
Check out the Velocity Systems Placards.