National Association for Stock Car Auto Racing (NASCAR) organizes several racing events across the United States each year. This format of car racing requires drivers to constantly step on the pedal to cover several laps of a circular circuit. While this might seem like an easy task, there are many roadblocks one needs to negotiate to even finish such races. Little wonder why accidents are a common occurrence on a NASCAR track. And here are some of the worst--and most spectacular--of the lot.