Gluttony. Invented during the time of Caesar. Day long banquets were accompanied by periodic vomiting and wild orgies. After losing momentum due to the fall of the Roman Empire, gluttony makes a strong comeback in the modern United States where 31% of citizens are obese - particularly tragic when you consider that there has been no corresponding rise in the percentage of Americans participating in wild orgies.
Prohibition(s). In 1919, popular demand for a prohibition on alcohol leads to the passage of the 18th Amendment – which results in the rise of Al Capone, Murder Incorporated, and the St. Valentine's Day Massacre. Despite this setback, a not very popular demand for a prohibition on drugs leads to the "War on Drugs" – which results in a corrections system that employs more people than GM, Ford and Wal-Mart combined, and Tommy Chong spending nine months in jail.
Creationism. 5 million years ago: Man descends from the ape. 1950s: For the first time, Darwin's Theory of Evolution becomes widely accepted outside of the scientific community. 1990s: "Intelligent Design" descends from the Discovery Institute. Shortly thereafter: Geologists detect the sound of Clarence Darrow spinning in his grave.
Virginity. After steadily declining in popularity after WWII - mostly once it was discovered that having sex involved the pleasurable activity of having sex – virginity has recently come back into vogue. One example is the Father-Daughter Purity Ball. Young girls and their fathers dress up, enjoy a night of fancy dinner and dancing and the girls pledge to keep their virginity until they are wed. Or until the next time there's a night of fancy dinner and dancing, like, say, at the prom. (Fathers pledge to "defend their daughter's purity." Some also pledge, "I shall not participate in a public stoning of my daughter even if things don't go according to my demented, patriarchal plan.")
Ralph Nader. The Green Party candidate's bid for the White House fell short in 2000, but he made a comeback as the Independent Party candidate in 2004 and is back once again as the Masochist Party candidate for 2008.
Floods, Pestilence and Boils. All three decline in popularity after the death of Moses. The advent of global warming has helped all three make a nice comeback, although you can usually avoid the last by wearing SPF 70.
The Bush Family Breaking Promises. 1990: George Bush breaks "no new taxes" promise. 2001: George W. breaks no "nation building" promise. 2008: Jenna Bush breaks promise to her mother not to marry someone even more white bread than George W.