Thanks to the nice folks at BoingBoing (and YouTube), I just watched two totally amazing videos. Apparently, in 1972 former Velvet Underground mates Lou Reed, John Cale and Nico were all touring Europe (separately) at the same time and decided to meet up in Paris for an unforgettable concert at a club called Le Bataclan. You can check both out below.
Lou Reed + John Cale - "Heroin"
Lou Reed + John Cale + Nico - "Femme Fatale"