Storage is a node.js compatible application that builds on Twitter-based identity to provide per-user storage for web applications.
For example, you could use Storage to build a system like Medium. It would be able to do most of what you need on the back-end for storage.
All web apps need to be able to store information on behalf of the user. We've had a couple of different approaches to work with that don't require an identity system -- cookies and local storage. These are good but the data is bound to a machine, not to a person. So if you went to a different machine, you'd have to start over.
Good for simple apps, but in order to get real utility, you need more.
With Fargo, we use Dropbox for storage. It comes with its own identity system.
However, when I tried to connect Fargo up to Twitter, all of a sudden there were two OAuth-based identity systems. I had so much trouble keeping track of it, I couldn't imagine most users being willing to go there. One identity system is enough.
The storage system we use is Amazon S3. The types of storage are the usual types you can store there. Graphics, movies, all kinds of text, JSON, XML, HTML.
Things like your preference settings are private, and HTML rendered from your writing is public. Storage supports both kinds, and the difference is just a boolean on an API call.