Years ago I created a series of tutorials for creating DotNetNuke modules, using a sample application called ThingsForSale.
The application allows Registered users to create posts of items they want to sale. They have to post their email address, because that is the only way for a visitor to contact them.
To demonstrate the productivity that LightSwitch provides, I recreated the application in LightSwitch, with the added feature that it allows visitors to send messages, and the poster to respond to them.
The entire application can be created in under an hour.
The tutorial is here:
I also have the application running live, in my DotNetNuke website here: