I’m not sure what exactly the interface for this would look like, but I would like a tool that:

• 
  Reads online calendar’s in various standard formats (iCal, RSS, hcalendar).
  



• 
  Allow a person to act as a filter, selecting which events seem worthwhile and interesting (which is different from committing to actually go).
  



• 
  Publish the results back to the web in various standard formats.
  

This would allow anyone to act as a sort of “social director” to a group of people who trust that persons tastes and interests.