Mike turned me onto a little calendaring site called Mosuki.  It's invitation only, and quite bare of bells and whistles--the about page says it was  "born from an academic inquiry into the mathematical properties of social networks."  But it's an interesting alternative or complement, as you will, to web calendars like Google Calendaring.  (I'm also looking at an fun social calendaring site called involver, which is in private alpha, and not yet sharable.) You add friends, they exist as a network, not many calendars laid on top of yours.  You can add these friends to different "groups" (I like the term playlists that the involver founders use) , and when you add an event, you indicate which parts of your network of the public can see it.  After that Events are browsable and "sharable" without any additional work on your friends' part. 

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