At Reboot7, people are doing collaborative note-taking using SubEthaEdit. It’s mind-blowing! It also means I can follow the 2-3 rooms I’m not in at any given time.
UPDATE: Trail-blazers here.
UPDATE: People are also using this to suggest and collaborate on questions for the presenter … in this case asking Skype why they don’t open up their IM network for interop with AOL/Yahoo/MSN.