For the past few weeks I have been working on a new project that I have called Calcium. Today, I did a simultaneous release of the source on CodePlex and published the first of a series of three or four articles describing its inner workings. I really like this project, and I highly recommend downloading the source code and taking it for a spin.
Calcium provides much of what one needs to rapidly build a multifaceted and sophisticated modular application. Includes a host of modules and services, and an infrastructure that is ready to use in your next application.