Hi everyone! I'm David Karger, a professor of Computer Science at MIT. I study and create systems that help people manage information. I started out in information retrieval and visualizations, but have since moved into the study of online discussion tools.
Our NB system (paper here) is a tool that looks at combining discussion with annotation, putting the discussion forum in the margins of the documents you want to discuss. It's primarily been targeted at education (course lecture notes, textbooks, and papers) and has been used in several hundred classes in dozens of universities around the world. We're figuring how to make online discussion an effective part of education.
We also study mailing lists. Amazingly, mailing lists have persisted---for over 40 years!---as a preferred tool for community discussion, despite there many obvious flaws. We've studied mailing lists and their users (paper here) and drawn conclusions about ways to fix their flaws without losing what makes them great. Based on what we learned, we've created Murmur, an experiment in reinventing mailing lists.
If you're a journalist, check out Tipsy, a Knight-prototype-funded experiment in driving donations to news sites. I'd love to talk to you about trying it on your site, which should take only 5 minutes to set up (honest!)