Perhaps this could be tied in with making the domain a little more complex. At the moment, the emails are just sent to a static email address when a new Author is added, but perhaps we can make this an email on user registration.

The app could be a service that allows users to create a set of favorite authors and books, or something like that.

There is a user model in lib/users and an auth config in lib/auth, but I haven't had time to work through the detail of it so the app isn't using any of it yet.