I’ve just completed work on another Facebook application: Songbook.
This was a relatively straight forward conversion of the existing application to use S3 for data storage. Songbook allows users to upload and display a song in their Facebook Profile. The original development stored the files on disk and hit limits really fast … hosting large numbers of files becomes very expensive very quickly, not to mention performance issues.
I converted the whole thing to S3 very quickly - it’s actually easier in some respects to handle storing files in S3 than to disk. The application now has essentially limitless and very cost-effective storage capacity.
S3 really is incredible.