Saw this thing on Cool Tools. It sure would help for hauling large sheet goods around inside a house. Handles plywood and drywall sheets with only one person. At $50, it's a bit steep for a homeowner who is just doing a small job, but for larger projects I think it would be great.
If you have an unemployed brother-in-law hanging around, save the $50 and have him help schlepp the boards and panels. If not, then use the lack of having an unemployed brother-in-law around as the best excuse to go out and buy one.
Seriously, if you do just one drywalling or panelling job in your home, it's more than paid for itself. I may get one to take with me to the home centers when I buy a sheet of plywood or particle board. Got to be easier than trying to wiggle a 4x8 onto those slotted carts.