Sometimes you wonder how Otis Jackson Jr. even finds time to sleep. The Californian hip-hop producer and rapper, better known as Madlib, churns records out at a rate so furious, that even dedicated beat heads struggle to keep up. His discography on the Stones Throw Records label Web site lists over 50 releases — as producer, remixer or artist — since 2004 alone. And they probably missed a few, too.

Madlib's distinctive jazz- and soul-inflected productions — the fruits of a life (mis)spent crate-digging in musty old record stores — have graced albums by the likes of De La Soul, Prince Po and Wildchild. He's delivered critically acclaimed collaborations with MF DOOM ("Madvillainy," as Madvillain), J Dilla ("Champion Sound," as Jaylib) and Talib Kweli ("Liberation").

Oh, and then there's the Blue Note remixes, two albums as helium-voiced alter ego Quasimoto, one as the dancefloor-friendly DJ Rels; the mix CDs; and innumerable releases under the umbrella of Yesterday's New Quintet, a jazz combo in which Jackson played all the instruments himself. Under aliases. To make matters more confusing, the latter recently split up — yes, imaginary groups can do that too — and reconfigured into no less than 10 different units, all of which will appear on the forthcoming Yesterday's Universe LP. And all of which, of course, are actually Jackson (although he does drag in a couple of drummers, Karriem Riggins and Mamao, this time).