In honor of today's date, 6-6-6:
The number 666 retains a peculiar significance in the culture and psychology of Western societies, where some perceive it as "the Devil's number", even in contexts usually remote from superstition. The fear of the number 666 is called hexakosioihexekontahexaphobia.
* When the CPU manufacturer Intel introduced the 666 MHz Pentium III in 1999, they chose to market it as the "Pentium III 667", claiming that, since the actual clock speed was 666.666 MHz, 667 was the more accurate approximation, against their usual rounding practice, examples of which are the 66.666 MHz "486-66", the 466.666 MHz "Celeron 466" and the later 866.666 MHz "Pentium III 866".
* U.S. Route 666, "the Highway of the Beast", was renumbered as U.S. Route 491 in 2003 after controversy over the supposed reference to the Biblical beast, which also made the road signs a common target for theft.