Finally an application in Ruby on Rails that goes beyond the usual example applications - and is not just a weblog or a totally pointless to-do list management or something similar: VitalSource is an iTunes-like application for books with a corresponding backend and a frontend also based on Rails (but integrated into the application):
Apparently their backend applications have been running Rails for a while. But they've recently released their client software, and it runs Rails as well. Except... you won't see it running in a conventional browser. As the picture shows, the Rails app runs embedded within the client executable: in the case of the Mac client it uses WebKit to render the responses from the Rails app.
I was already fed up with all the Rails applications - which all sounded like textbook exercises.