Like what Rick Rubin does. As far as I know he has never written or recorded a song of his own, but he has been a key part of the creation and recording process of an incredibly wide range of genres and a stunning number of the best albums of their time....
I have such specific tastes in music, I want to be able to find the people who also find stuff I dig. Like the ultimate version of Pandora. But also the ability to collaborate on music, like the way producers alter songs to the flavor they like, but a bunch of folks could do that...