If you haven't already, read What You Should Know About 2012. Not just an un-useless debunking but an interesting history of yet another silly idea.

The significance of the date was popularized during a counterculture event known as the Harmonic Convergence that was organized by [José] Argüelles ... who thought that the problems of Western civilization were due to the use of a calendar that was not directly linked to the movements of the Sun, the Moon, the planets, and the stars. He sought to revive a version of the Maya calendar based on solar and lunar cycles, creating a new system that he called the Dreamspell....

The Harmonic Convergence... was promoted using new computer technology ... and early computer networks. Since the 1960s, interest in astrology, Tarot, the I Ching, and the Maya calendar had been widespread among programmers associated with the new personal computer and software industry in what was to become Silicon Valley in northern California. Counterculture and New Age concepts ... had been a part of cyberculture since its inception, so it was only natural that early digital social networks ... played a role in spreading the word about the Harmonic Convergence and 2012 among psychedelic and computer "hacker" subcultures that frequently overlapped...

As computer networks grew, the ideas spread among individuals using the World Wide Web... People created websites promoting the idea of either: 1) the literal end of the world, or 2) a spiritual transformation. However, this happened independent of academic scholarship on the ancient Maya, which did not support the idea of any "prophecy" or either scenario. The "prophecies" about 2012 are best considered a kind of folk mythology of the digital age, a collection of myths and legends that are spreading via commercial publications, television, and especially digital computer networks. The attention being given to the Maya date 13.0.0.0.0 4 Ajaw 3 K'ank'in (December 21, 2012) is largely the result of persistent folk beliefs about astrology, numerology, mysticism, and revelation. (Notice, for example, the unusual appearance of the numbers "13.0.0.0.0" and "12-21-12".)