Gotta have one! I've had the aluminum contractor style, and they are built to out-last 2 or 3 pickups (at least the A.R.E. brand is.) My newest one is an A.R.E. fiberglass with hinged access doors on both sides, rack on top to haul the kayaks. And as others have stated, you can lock your stuff up and it stays dry when it rains.
A.R.E. calls their contractor model the DCU (for Deluxe Commercial Unit) You can play around with different configurations of all the A.R.E. models on their website, and also get the name of the nearest dealer. http://www.4are.com/