[I had to call this out because I think its a cool example of what can be done with SSDS.]
Mike Amundsen is a guy that really grasped the SSDS nettle. First he built the SSDS provisioning client (http://amundsen.com/examples/ssds/data-client/) and now he's built a simple application that is basically a Twitter clone, see it at http://amundsen.com/examples/ssds/guestbook-client/. As Mike himself says:
This demo application was built to explore Microsoft's SSDS cloud database services. It was built using C#/ASP.NET on the server and a simple HTML/Javascript client. You can get details on this and other samples at the SSDS Examples web page.
This application was built using a single SSDS Container (guestbook) with multiple SSDS Entity "Kinds" (message and guest). The server code handles user authentication using either standard HTTP Basic or a custom cookie (x-forms-authorization). This makes it possible to use either a web browser or standard HTTP request services to interact with the database.
Its not going to topple Twitter of course but its a great example of what can be achieved using a data service. No worrying about machine hosting, database administration or scaling-out ... the service abstracts us away from all of that.
Go check it out: http://amundsen.com/examples/ssds/guestbook-client/
-Jamie