20. Aaliyah Almost Misses Her Set (2000)
R&B princess Aaliyah was running so late for her spot at Summer Jam 2000 that she nearly didn't get a chance to perform. By the time she made it to the stage her dancers didn't even have time to change out of their street clothes. The crowd didn't care one bit though, greeting her with open arms. Her performance that year was one in a million—and then the next year she was gone.