Sampled: Iron Butterfly

If you're mostly familiar with Iron Butterfly thanks to a one-off joke on The Simpsons, perhaps a few rappers can give you a brief lesson about the '60s psychedelic rock band. From hip-hop greats like OutKast, Nas and the Beastie Boys to almost-forgotten underground stars like Poor Righteous Teachers, nod your head to cuts that sample the English rockers.