General fact: 5 is the number of interlocked rings in the symbol of the Olympic Games, representing the number of inhabited continents represented by the Olympians (counting North America and South America as one continent).
Mathematical fact: 5 is the second Sierpinski number of the first kind, and can be written as S2=(22)+1.
Trivia: 5 is the most common number of gears for automobiles with manual transmission.
Historical date: January 5th is the day in 1975 that the Tasman Bridge in Tasmania, Australia, is struck by the bulk ore carrier Lake Illawarra, killing twelve people.