I noticed this past weekend on the douglas run, that one vehicle had Molle panel on the inside of the rear door. I have been of a mind to by surplus molle panels from ebay that we made to fit military hummers front seat backs. About $20. Any military pouches or after market copies will all fit. Pouches and panels can be purchased from Ebay, amazon and any surplus outlets. I can think of almost infinite uses from first aid kits, fire kits, tool sets, etc etc. Pouches could be attached with molle webbing or velcro panels for quick grab n go uses. I think they would be a great way to organize your overland rig and put commonly used items close to hand when your on the road.
Please chime in and tell us what YOU would put them to use for, or what you may use them for.
I stumbled across this old thread and recently put some Coverking Tactical Seat Covers with MOLLE backs into my Silverado dually (from Costco, which I'm a nerd for). Love them. Great for small gear, kid stuff, and a few cleaning supplies. It's also fun for me and the kids to decorate things with velcro patches - these seat covers have velcro backing between the MOLLE straps.
I have the Rago Fabrication modular storage panels in the rear of the 4runner. Not sure if those are what you saw. They are very handy. I have a first aid kit and several pouches attached to them that contain basic travel necessities in them.