BeerBorg

Well, not a deal but a great idea for those who have everything from 3 gallon to 6.5 gallon plastic and glass carboys and have to lug them up and down stairs and move them around often. $20.....that's not too bad, is it?
http://www.carboy.net/

I think if you use more than one carboy, some kind of dedicated carrier is a good idea.
I just have one, so a re-usable nylon shopping bag does the trick.