I built Norm's clamp cart last year and it has been a pleasure. I don't have it on wheels, but positioned it so that I can access front & back. The great thing about it is that it will hold 6 footers all the way down to jorgensens & spring clamps. Everything is in one place.
Before the cart, I had them hanging on the wall on a 2x4, but this was a real PITA and some clamps did not conform (like quick clamps & small spring claps). Some would fall off at times.
Anyway, for the cost of a few pieces of lumber and a few hours, it is definitely worth considering a clamp cart.
Lou