Amazon introduced their new storage for web-services, S3. You can access the storage with SOAP and REST to store, get and delete files. Sounds like just another FTP? Well, something like that, but with some advantages.
Amazon advertises that it is a reliable, simple, fast and cheap way to store data. The pricing is simple, 0.20 $ for each transfered GB and 0.15 $ for each stored GB/Month.
There are a few uses I can imagine.
1. You could build a software to use it as inet-storage for private data.
2. You could frequently backup your webapplications / websites.
3. You could use it as seed to distribute files via bittorrent.
Amazon does not tell how they secure your data. So if you use it for backup I would encrypt the data first.There are some nice examples at the Amazon-Web-Services-Developer-Connection