A widespread conspiracy theory concerns the EAN or UPC bar codes, instituted in 1974, and found on most consumer products. The "control codes" in the left, middle, and right of the code appear on initial inspection to represent the number "6". Because of this, all EAN/UPC codes (so the theory goes) contain the number 666. One interpretation of the Book of Revelation indicates that the Number of the Beast is required for all business transactions a role that the EAN/UPC code certainly fits. Also the inventor of the UPC code, George J. Laurer, has six letters in his first, middle, and last name [4], and, as of 2004, exactly 666 prefixes (out of possible 1000) are assigned in the EAN-13 namespace [5]. (Unfortunately, the control codes only appear to represent the number six if one is unaware that both the black bars and the spaces in between them are used to encode information.)
The anti-impotence drug Viagra has a molecular weight of 666.7 g/mol.
In the Dutch translation of Dan Brown's best-selling novel Angels and Demons (translated title Het Bernini Mysterie), the discussion of 666 is on page 333. 333 is 666 divided by 2. The numbers 2 and 5 have special significance to the Illuminati, a group that is pivotal to the novel's plot.
In Marvel Comics, parallel universes are represented by numbers. The main Marvel Universe (which is also supposed to be the same universe as ours) is known as Universe 616.
In Japan, the yen comes in coins of 1, 5, 10, 50, 100 and 500. If you have one of each coin, you have 666 yen.
In one formula, where A=100, B=101, etc., until Z=125, the name Hitler adds up to 666 when the values of each letter are added. It was apparently speculated thusly that Adolf Hitler was the antichrist.
Astrology
On 06/06/06 (June 6, 2006) the sun will be between the horns of Zodiac sign Taurus.
Computer-related
The octal number 666 is used in setting up authorizations in the Unix Operating System. It offers read and write access to all users, and is only limited by the permissions of directories above or different permission schemes, e.g. ACLs. This matches the Revelation ('13:17 And that no man might buy or sell, save he that had the Mark, or the name of the beast, or the number of his name. ') in that this could be a way to allow or disallow people to buy anything (the Mark of the Beast as a personal body mark easily readable by automated cashiers in a cashless society).
This also leads to speculations that software manufacturer Microsoft, and its founder, Bill Gates, are evil [7], as
Bill Gates, evaluated in ASCII, sums up to 663, which, when added with 3 (his complete name is William Henry Gates III,) becomes 666. Counting the space as one, Windows 95 also sums to 666.
The sixth letter of the Hebrew alphabet is "waw" (or "vav"). This is the closest approximation of the English letter "w". Also in the Hollerith Card (sometimes called an IBM Punch-Card) a zero zone punch and a six numeric punch in a column signified the letter W.
Thus the ubiquitous acronym "www" could be the Number of the Beast.
Also, the number 6 in Roman numerals is represented as VI. 666 = VIVIVI, and it has been suggested that visions from the past mistook WWW for it (In the time revelations was written, U, represented as V, had the sounds U and W, which lends this support).
Another speculation is that computer=666. If we encode the English alphabet where every letter is a multiple of 6: a=6, b=12, c=18, ..., z=156 then we have "computer" = 666 = (3*6)+(15*6)+(13*6)+(16*6)+(21*6)+(20*6)+(5*6)+(18*6). Since "beasts" such as oxen, horses and donkeys were used as machines in ancient times, one can infer beast in modern times meaning "machine" or "computer". Since computers were developed by English speaking people it is plausible that the numerical decoding should be via English, such that one interprets leading the development as riding the head of the beast.
TCP/IP port 666 is officially registered to ID Software, the publishers of the Doom series of games, for multiplayer game communication across a network; this is obviously a gimmick. Port 616 is officially registered to SCO System Administration Server, much to the amusement of SCO's critics.
The size of Google's Web API Developer's Kit is 666k.
more here :
http://en.wikipedia.org/wiki/Mark_of_the_Beast#Avoiding_the_number