6th June 2006 - 6/6/06
Recent discoveries show that 616 to be the Number of the Beast, rather than the more commonly accepted 666 - in 2005, an early fragment of papyrus was discovered, showing that the Number of the Beast was 616. The reading 616 is intriguing since the conversion of Nero Caesar's name in Latin by way of gematria (Hebrew numerology) comes out to 616.
UPDATE: Most scholars agree that the Number of the Beast is 666, and not the recently discovered 616. Hat tip to Fr John (see comments for more details).
There is a theory regarding the meaning of 666. Man was created on the 6th day and Triune God exists in 3 persons - Father, Son and Holy Spirit. Therefore, the number 6 represents Man and the fact that it is repeated thrice implies than Man is trying to be God.
More Useless Facts About the Most Dreaded Number:
666 written in Roman numerals (DCLXVI) is the only number that uses once each the Roman number symbols with values under 1000 and they occur in exact reverse of their respective values (D=500, C=100, L=50, X=10, V=5, I=1).
Apple's first computer, the Apple I, was priced at $666.66.
666 is an abundant number. It is the sum of the squares of the first seven prime numbers.
666 is the numerical value of "ועתה יגדל-נא כח אדני" [Ata yigdal na koach Adonai - Now, let the power of my Lord grow] (Numbers 14:17). This was Moshe's prayer invoking Divine Mercy on behalf of the Jewish people.
666 is the brand of a cough syrup in the United States.