1. The ability, through Office update, to download and display a list of
holidays to display on the calendar.  Select holidays or holiday groups to
filter out.

2. For example, if I'm Jewish or Buddhist, I might not care to see
Christmas, Easter, etc.  Or vice versa.

3. This might open up a cool opportunity to create holiday-ish icons on
calendar days, which could optionally be links to holiday websites, or just
tooltip-like pop-up windows describing what the holiday is about, a short
history and description, etc.

4. Set up reminders on certain holidays.