This is just what I was looking for.  I needed a carrier for the airlines for my dog, this is perfect.  Not only is it on wheels, but the perfect size for my small dog, under 10 pounds, but for my cats as well.  I plan to use it for toting my cats to the vet.
My only concern is that I am not sure how I will handle my wheeled luggage and my wheeled carrier.  I know I can also use the carrier as a back pack though.