Google CalendarApril 13, 2006
Google Calendar looks pretty slick so far. Really does for webcalendars what gmail does for webmail.
Doesn't seem to support some kind of syncing with Evolution or Sunbird though (from looking at the interface). It does support iCal and CSV import so maybe the export functionality is only a matter of time.
UPDATE: What I forgot to mention is that it can be read from an iCal supporting client. You can't remotely publish though.