063 / Mos Def & Talib Kweli are Black Star by Black Star, 1998
"The album's fruition came about from the chemistry between the two emcees. Both planned to release their solo albums around the same time, but they postponed their individual projects and decided instead to collaborate on a full-length LP." via Wikipedia.
Mos Def x Talib Kweli are like my collaboration dream. You hear about Bonnie and Clyde or peanut butter and jelly -- but this is my ultimate duo. I would like to find my Kweli... or my Mos Def.