Evidently I’m the last to know about this:

Castle Church is an online social bookmarking community for Christian reformed theology. We view the community as sort of a living bibliography. Our purpose is to provide a space for students of reformed theology to collect, organize and share reformed resources from around the Internet. We desire to be everyone’s online research assistant.
On October 31, 1517 Martin Luther nailed his famous 95 Theses to the door of the Schlosskirche (Castle Church) in Wittenberg. Our Castle Church is a place for you to “nail” a variety of reformed theological resources to a virtual door. We support the organization of articles, books, links to other sites, audio and video lectures.

Looks like it will be a great tool. Sort of like digg for the reformed community.