For those who haven’t already, check this nifty remix/mash-up of Radiohead vs. Roots: “Nothing in its right place”. The remix is done by DJ BC and available for download at djbc.net
Couple of other favs here are the Flaming Lips vs. Snoop Dogg, “Yoshimi Battles Snoop Dogg” and The Beaties vs. Kraftwerk, “Intergalactic Robots.”
