Sorry if you guys have already seen this, but it just blows my tiny mind:
James Brown and Luciano Pavarotti together again for the first time.
Seriously, this is crossover gone totally gonzo amuck. The only thing I can imagine to top this would be something interspecies -- Celine Dion and Shamu the Whale dueting on "Louie Louie," maybe.
[h/t Steve Early]