LightSwicth is a new development tool by Microsoft, targeting power-users and non-professional developers, willing to write data-oriented business applications.
LightSwitch can bee seen as a kind of "VB / Access for the Cloud".
The tool is quite complete and easy to use by default but it also provides a lot of customization features.
Here is a good introduction video:
and another one showing extension capabilities:
The LightSwitch pages:
http://msdn.microsoft.com/en-us/lightswitch/default (downloads, examples, trainings...)
It is currently in Beta2 stage, but it is stable enough to be seriously evaluated.