Zulu Nylon Gear, an Illinois based custom "tactical nylon" company, has an interesting take on the traditional messenger bag - the Emissary. The Emissary is approximately 12" x 15" x 5". It's available in brown, black, MultiCam and foliage. It features a wide hook-and-loop panel across the front (slick front available), with multiple zippered pockets both inside and out as well as front and back. There is also a mesh water/Nalgene bottle pouch on one end balanced by MOLLE panels on the other. Internal pockets can be accessed without unbuckling the flap and the main internal compartment is lined with hook tape to allow for modular placement of additional pouches. There are MOLLE Panels on the exterior and a pair of loops underneath for stowage that are secured with shock cord. The interior of the hinged lid -- which buckles down to the main body-- features a clear plastic cover to protect documents or other sensitive objects.
The Emissary retails for $249.00 and is typically not in stock. They are sewn to order, so delivery may take as long as 4-6 weeks. You can order one here. I first started following Zulu Nylon Gear a couple of years ago when I read a review of their magazine pouches on Death Valley Magazine. They have since come out with a few new items and continue to receive good reviews.
Zulu Nylon Gear is sewn not just in the US, but in Chicago. I clarify that mostly because I want to say, "That's the Chicago way!"