I had this _exact_ idea when Glacier came out, and even registered a domain with a splash page. Still thinking about building it but lacking time. I was looking at specifically storing RAW files for photographers and generating low-res versions to show in some sort of library.
Had exactly the same idea myself. Whoever makes it work first is probably onto a winner (I probably won't pursue it myself due to lack of time, but I'd love to use such a service).
