Rooted in New Orleans's rich music culture, No Limit mogul Master P and bounce breakouts DJ Jimi and Juvenile shake rap and put twerking on the map.

Auteurs like the Neptunes' Pharrell and Chad expand the sonic palette. Timbaland and Missy Elliott lean forward. Kanye West and J Dilla reimagine rap.

Mixtapes spread the hottest sounds, infringe copyright and break artists. Among them, 50 Cent polarizes, T.I. takes off with trap, and Lil Wayne clicks.