It's one thing to see our favorite actresses and singers doing their usual routine, but once they start working their hips, that's when the magic happens. Today, we have Demi Moore, Salma Hayek, Lindsay Lohan, Jennifer Lopez, Jessica Biel and Rihanna in all of their rump-shaking glory. Heck, we even threw in some Christina Aguilera dirrty dancing from back in her prime.