Best musical duos?

I love everybody named so far! But, don't forget: The Everly Brothers, The Righteous Brothers, The Blues Brothers, Steeley Dan, Jan and Dean, The Carpenters, Sonny & Cher, The Pet Shop Boys, Seals and Croft, Jimmy Page and Robert Plant, Evanescence, Erasure, Peaches & Herb, Indigo Girls, and, yes, even Air Supply. :) Hey, I like them. Go ahead and laugh. :)