Before next class, I'd like you to sign up for two services.
Medium is a service that enables friends to share presence while on the Web -- you can see where your friends are online when you're using Medium at the same time. StumbleUpon helps you bring the serendipitous browsing we experience in bookstores and other settings to your Web experience -- by randomizing the Web in a somewhat controlled manner.
You can get a sense of how we might use the two tools in class together by reading this post in my personal blog, Media Diet: "On Serendipitous Browsing."
I've already used the two tools with some of the people I work with, and I think we'll enjoy them. Let me know if you have any trouble signing up for the respective services.