Portable Litter Boxes

I had an encounter once with an entrepreneur that had invented something that I had never thought would be a necessity--- a portable litter box. The box itself was made out of cardboard, so once it had been used once or twice (about the number of times one would use it on a road trip), it could be disposed of without having to worry about cleaning it and bringing it home. I've never been one to travel with cats, but having owned one (a cat), I can definitely see how having a portable litter box would be quite helpful. As far as I know, the gentleman has been quite successful with his invention.