Dynamic updates to shared date-specific data, including the weather. Now if only I could sync Google calendar with Outlook, or the OS X calendar, or even my (yech) PalmOS PDA.
Update 9/27/06: I got a link from Jacob Reider's blog to an ultimate sync post and to ScheduleWorld. Wow. That sync guy is one serious geek (that's a compliment coming from me). I'll have to decipher it and see if this could really work ... I wonder if Jacob posted that one after seeing my post -- I know he reads this sometimes (though Gordon's Tech doesn't go to Jacob's medlogs site).