"So far, our application, aggroGator, allows a user to mash up several popular Web services and create an aggregate feed of those services. Now, to make things a little more interesting, we want to allow users to subscribe to other users' feeds (where each user's feed is quite possibly an aggregate of feeds itself.) For example, let's say we want to set up an account to subscribe to ourself on Twitter, last.fm, and del.icio.us, so friends can then subscribe to our aggroGator feed to see all of the activity on those services. To handle this, we need to once again revisit our data model."
