Actually, 666 isn't the date to worry about. They say that 666 is the number of the beast, but that is actually written upside down. 666 actually means 999. As in: 999, 1999, 2999, etc. And then we go biblical.
Revelation 20:
6 Blessed and holy are those who have part in the first resurrection. The second death has no power over them, but they will be priests of God and of Christ and will reign with him for a thousand years.
7 When the thousand years are over, Satan will be released from his prison
8 and will go out to deceive the nations in the four corners of the earth --Gog and Magog-- to gather them for battle. In number they are like the sand on the seashore.
9 They marched across the breadth of the earth and surrounded the camp of God's people, the city he loves. But fire came down from heaven and devoured them.
10 And the devil, who deceived them, was thrown into the lake of burning sulfur, where the beast and the false prophet had been thrown. They will be tormented day and night for ever and ever.
It is the Millenium shift. If you're supersticious or interested in it, you can always take a look at the things that happened after December 31, 1999. In the last 5 years we've had Tsunamis, tons of hurricanes, the 9/11 attack, the attack in London, the attack in Paris, the assassination of Pim Fortuyn and Theo van Gogh in the Netherlands, Bush in office
, pointless wars in Iraq and Afganistan where hundreds of our soldiers don't come back from, etc etc.
Some say the devil did play his cards. It doesn't scare me though. If anything, I believe God and the devil are simply playing chess up there. The balance of power. Everything in this universe needs balance to exist. That is why our world and it's inhabitants know both good and evil.