ccmixter.org is a community music site featuring remixes licensed under Creative Commons, where you can listen to, sample, mash-up, or interact with music in whatever way you want.
They are sponsoring a contest for artists to mix audio tracks under 4 minutes which use provided voice samples from Ben Franzen and Kembrew McLeod's forthcoming film, "Copyright Criminals." Samples from the film include voiceovers from De La Soul, DJ Qbert, members of Public Enemy, Matmos, Coldcut, members of Negativland, and others. The best overall winner will be included prominently in the film and the top 11 other entries are to be included on a companion CD. Judging entries along with McLeod and Franzen is Jeff Chang, author of the American Book Award-winning "Can't Stop Won't Stop: A History of the Hip-Hop Generation" and co-founder of the influential label SoleSides (now Quannum Projects), responsible for launching the careers of DJ Shadow, Blackalicious, Lyrics Born and Lateef the Truth Speaker.
UPDATE: As of February 15, 2006 the official end date for the Copyright Criminals Contest is now March 14, 2006. All other rules are the same. Also, new samples from George Clinton (Parliament-Funkadelic) and Chuck D (Public Enemy) are added to the list of possible source material that you may use.