Hip-hop is the first commercial art form to take on postmodernism's infatuation with the cut-and-paste aesthetic, and it continues to break new ground sonically and culturally. When early critics of the genre declared that hip-hop "wasn't real music," they were paying it a much higher compliment than they could have ever realized. After all, this wasn't real music, at least how we then knew it. Hip-hop, both in sound and structure, was something bracingly new, perhaps the biggest departure from the status quo since rock 'n' rollers plugged in their guitars three decades before. In this sense, all hip-hop is experimental. But even in a genre that values all things new and different, there are some acts that stand out. While this innovation takes place in the commercial realm, it is most pronounced in the underground circles. At times, this innovation is calculated to fit into a larger, music history context. The work of acts such as Dalek, DJ Spooky and Anticon are self-consciously different -- the result of cross-referencing Lacan, Stockhausen and Chuck D. Meanwhile, other innovations appear more organically. The turntable scratch, for example, was the result of early DJ Grand Master Theodore accidentally laying his hand on the record when his mother knocked on the door. Oftentimes these aberrations are considered the hip-hop equivalent of outsider art until they are codified by mainstream acts. What hip-hop has in store next is anyone's guess. Technology continues to push the genre forward, keeping it fresh while divorcing it from its original intent.