That's the dirty little secret of a lot of web storage and hosting sites. They can sell you gigs upon gigs of storage because in all likelihood, you'll never use all of it, or by the time you do, storage will have come down in price.

Sure there are some users who will max out their accounts, but those will be averaged by those who hardly use any.

As a person working on a web storage product, I'll tell you that's not a dirty little secret--it's our business.

Sound's very loosely like fractional banking. What percent do you have to keep on hand per user in order to prevent maxing out the storage capacity? Or do you just let it max out and then add more storage?