The Museum of Hoaxes has a list of the Top 100 Hoaxes of all time.

Here are two of them for your enjoyment on this April Fool's Day....

#79: PETA’s Tournament of Sleeping Fish
In 2000 the People for the Ethical Treatment of Animals (PETA) warned that it planned to sabotage the bass fishing tournament in East Texas's Lake Palestine by releasing tranquilizers into the lake before the tournament. Their announcement stated that "this year, the fish will be napping, not nibbling." State officials took the threat seriously and stationed rangers around the lake in order to stop any tranquilizer-toting PETA activists from drugging the fish, and numerous newspapers reported the threat. Eventually PETA admitted that it had been joking.

#80: Moscow’s Second Subway
In 1992 the Moskovskaya Pravda announced that the winds of capitalism transforming Russia would bring further changes for the residents of Moscow. Apparently plans had been finalized to build a new Moscow subway system. Of course, there was nothing wrong with the city's current subway. But in the spirit of capitalism, the second system would be built to promote "the interests of competition."