Skateboarders know that an ollie is a basic skateboarding trick, where the skater slams his back foot on the end of the moving board, and jumps, popping both himself and the board into the air. It was invented by a skater named Alan Gelfand, whose nickname is "Ollie." Though there are those who think that skateboarding was invented by Marty McFly in 1955, it's actually been around in more primitive forms since long before then. The skateboard craze hit an early peak in the '60s. The invention of the ollie helped revitalize the sport; skateparks encouraged more skaters to take to their boards. In 1995, ESPN inaugurated its X-Games, featuring competitions in extreme sports like bungee jumping, biking and sky-surfing. Skateboarding was also one of those sports that gained new momentum when it was included in the X-Games. Today is Go Skateboarding Day. Don't forget your helmet!