Lailat al Qadr... the Night of Power (also translated Night of Determination)
Islam holds that this marks the night when the Qu'ran was first revealed to Mohamed.
Muslims believe that this is the night that the fate of the world for the coming year is determined. It is considered to be better than 1000 nights.
(Side note: I've wondered for years whether this was the origin of 1001 Nights - Tales of the Arabian Nights - or Al Laila wa Laila - 1000 nights and a night - but I digress.)
Some Muslims celebrate it on the 27th day of Ramadan; no where in the Qu'ran is the exact day specified, although the Prophet Mohamed is believed to have said it falls within the last 10 days. When I was in Cairo, I was taught that it was one of the odd numbered days during the last 10 days.
I remember our discussion on the Arabian nights well...I'm just getting rattled this year I guess
~sigh
29 is a prime number, so is 11, 19...