Steel Horse Automotive makes the HitchHand, a T-shaped bracket mounted to square steel tubing that slides into the receiver. The sides of the bracket expand to 49 inches in width, and the unit will accommodate loads up to 750 pounds. And this list barely scratches the surface of what's available for your truck bed. Tube-frame extenders hold cargo when the tailgate is down. Diamond-plate caps protect your bed rails and tailgate from dings and dents.
Cargo nets keep groceries and other small goods from spilling.
Ramps make loading ATVs easier. Steps that slide over your back tires help access to cargo. You name it, it's probably being made for your truck bed. Or it's on some designer's drafting table.