The SF garage my fiancee parks in has this thing made from an industrial belt, with steps bolted onto it. I think there are quite a few of those in Stuttgart as well, though they are being fazed out. It's very efficient, but not for ze stupits!
I saw one like this as a child, in Chicago. As I remember, it was explicitly only for the employees to use to get to the cars, as it was a valet facility.
