The Notorious B.I.G. - The Ugliest (Prod. J Dilla) feat. Busta Rhymes & Talib Kweli 
Did you know that while alive, Biggie recorded on an original J Dilla beat? This is not a mash-up. Features a young Talib Kweli on the hook, as well. BIG’s verse eventually ended up on Dangerous MCs from his posthumous release Born Again.