In the book Predictions for the Year 1708, a soothsayer going by the name of Isaac Bickerstaff made the prediction that John Partridge, a cobbler turned astrologer who was the editor of a rival almanac, Merlinus Liberatus, would die on March 29 around 11:00 p.m. of a raging fever. On March 30, Bickerstaff published a pamphlet claiming that the prediction had come true, Partridge having died within four hours of the predicted time, and that on his deathbed he had even confessed that he was a charlatan. Partridge was still alive, however, and protested that the report was entirely false, even advertising that fact in newspapers. Bickerstaff, together with other writers, continued to insist that Partridge was in fact dead and that the man claiming to be Partridge was an imposter. Partridge lived another seven years, most of which were spent struggling to prove his existence and discover who Bickerstaff was. He never did discover that Bickerstaff was Jonathan Swift, who was better known for Gulliver's Travels. (source)
According to some interpretations of the Mayan "long count" linear calendar, the end of the world was to have happened in 2012.
In 1213, Pope Innocent III wrote that the end of the work was coming in 1284. He arrived at this date by adding 666, a number mentioned in the Book of Revelation, to the date of the founding of Islam in 622. (source)
In August 1820, an avalanche on Mont Blanc swept a nine-man team of mountaineers into a glacial crevasse on the mountainside. Local people who knew the rate at which the glacier was moving calculated that in 40 years the bodies would appear at the foot of the mountain in the Chamonix valley, some 8 kilometres from where they had died. The bodies appeared in 1861, only a year later than predicted, and still looked "in the bloom of youth", according to some reports.
A terrifying forecast known as the "Toledo letter" circulated in western Europe in 1185. Johannes, a Spanish astronomer, predicted dire weather when all the known planets came into conjunction (aligned with each other) in September the next year. He predicted that ferocious winds would destroy most buildings, and famine and other disasters would follow. Many people took precautions against this calamity—some even built shelters underground—but the cataclysm failed to materialise.
In 1967, Keuffel & Esser, a maker of slide rules, commissioned a study of the future. The report predicted that, by the year 2067, Americans would live in domed cities and watch three-dimensional television. Unfortunately for the company, the report failed to predict that slide rules would be obsolete in under ten years, to be replaced by the pocket calculator. By 1976, Keuffel & Esser, who were now selling Texas Instruments calculators much faster than the slide rules that made up only 5% of their sales, mothballed its slide rule manufacturing equipment and sent it to the Smithsonian Institution. (source)
In 1936, Literary Digest magazine polled 10 million people using the telephone and its mailing list to try to predict the outcome of the United States presidential election, more people than in any previous presidential election survey. Their results indicated that Alf Landon, the Republican candidate, would defeat Franklin Roosevelt, the Democratic candidate, by a margin of 370 electoral votes to 161; however, in the election, Landon was trounced by Roosevelt by a margin of 523 electoral votes to 8, at the time the largest landslide in a contested presidential election. The problem with the survey was that, during the Great Depression, telephones and magazine subscriptions were luxuries that not everybody could afford. Those who could afford such luxuries tended to vote Republican, but the voting public in general was more inclined to vote Democrat. (source)