30. "Welcome to the Jungle," Guns N' Roses (1987): You know you've scored a killer riff when it becomes a staple at all major sporting events to fire up a crowd. The first song ever co-written by Slash and Axl Rose, "Welcome to the Jungle" was the second single from Guns N' Roses landmark 1987 debut album Appetite for Destruction. In his autobiography, Slash says it was Axl who remembered and reminded him of the classic riff when GN'R were first starting to write songs together. The Chapeaued Shredder originally conjured "Jungle's" riff while shacking up in his mother's basement. – Sean Patrick Dooley