VSTO Contrib is all about making VSTO development better for developers. It allows you to separate your concerns, use IoC and write more testable clean code in your VSTO add-ins
This project is also hosted at http://vstocontrib.codeplex.com/, feel free to submit PR's at either location.
A getting started video is available at http://youtu.be/TxRjNsaVX6U