Further to the last post, may I present:
2008-2009 All Holidays Calendar (version one)
Running from June 1 2008 to May 31 2009, this includes approximate sunset times, as well as all the more important (i.e. to be taken-off) holidays I could find.
www.interfaithcalendar.org is a kick-ass resource for this, btw
Of course, some of the dates are also approximate, but it's interesting how some of the holidays seem to align. I wonder if this would be feasible...
And please let me know about any errors!