I like the duets that have rappers in them the best for some reason.
Eminem & Rihanna - Love The Way You Lie
Eminem & Dido - Stan
Eminem & Rihanna - The Monster
Tinie Tempah & Eric Turner - Written In The Stars
Tinie Tempah & Labyrinth - Pass Out
There are other ones involving rappers in duets, but I don't want the post to be like a Picture Book.