"Whatsup" is a simple version of the "what are you doing right now" functionality you find on Facebook and other sites. Whatsup lets you post your name and status and view the statuses of others. Here's what it looks like.
When you access the page, you see the recent status of others. If you enter your name and status and click Post, the page updates to show your status top most.
Obviously this isn't a terribly sophisticated program, but it does make a nice transition from "Hello, Cloud" to something more substantail. You can actually build this app from scratch in front of an audience and deploy to the cloud in 30-45 minutes which makes this great for user groups and training sessions.
Whatsup is an ASP.NET application that also uses SQL Data Services for storage. I had planned to leave a hosted version of whatsup online for public access, but it appears the dev Azure accounts have a 1-project limitation :( ... and I need to move on to develop more apps.