* Ensure timezone information is retained
 
* Improved set of TripIt methods
 
* Other specialized methods (say, for GCalendar or ICal feeds)
 
* Higher-level methods (say, "privatize" to replace all information with
  a "Private" or "Busy" description)
 
* Some date manipulation methods (e.g., my calendar might have the actual
  appointment time for some events, but for display to others I might want
  to enlarge it to incorporate travel time to and from)
 
* Similar to the cgi module, it should be easy to require modules
  to turn a filter into a camping app, a webrick service, etc.
 
* Perhaps have real methods for filter_{events,freebusys,journals,todos}
  to improve the rdocs.