Tomorrow marks the end of the 13th cycle of the ancient Mayan calendar, giving rise to rumors about the end of the world. Worries about a looming apocalypse are nothing new in human history, but 21st century reactions to the possible destruction of the planet (or human civilization) vary widely, from "preppers" who cultivate self-sufficiency, to groups offering prayerful wishes, to entrepreneurs who have found a growing market for their survival gear. Regarding tomorrow's fateful date, the descendents of the Mayans themselves appear to regard the milestone as simply marking the end of an era, not the entire world.