Saw some quite amusing coverage concerning today's date on the BBC website, called the Nick of Time. It all centres around the fact that today is 06/06/06 or 666 if you are going to be dramatic about it. You can enjoy the Beeb's coverage here Rather in the same way that the Millennium (that's two 'l's and two 'n's) occupied some people's imaginations to a superstitious degree, so the number 666 seems to have a grip on certain kinds of Christians (ironically the ones who would be most damning of anyone being superstitious!)
The number itself gets dismissed by one Satanist group as a Christian number, but at least it's an excuse for a good party. The origin is of course the number of the Beast in the book of Revelation (Rev 13:18). The best explanation I have seen is that it is a way of naming Emperor Nero in code - that's the way the whole book works, as far as I can see. I quote from the BBC again:
"One theory is that the letters "add up", in the form of numerology called Gematria, to Nero or "Neron Caesar", written as "Nrwn Qsr" in Hebrew letters
r = 200; s = 60; q = 100; n = 50; w = 6; r = 200; n = 50 Total: 666"
It all comes down to a rather arbitrary calculations of dates and times, and no doubt it will be marked by occultists and Christians alike for very different reasons. Personally I won't be joining either of them!