Here is a link to the sobrenatural música Guide on Supernatural.TV link It has Seasons 1-4 and lists the música played in each episode. I think the S4 list is incomplete but I'm sure they'll finish it eventually.
My favorito ones in the show are carry on my wayward son-Kansas (all seasons) You Shook Me-AC/DC (Season 4) Lonely Is The Night-Billy Squire (Season 4) In A Gadda La Vida- Iron borboleta (Season 1 haha old I know but I amor that song) Crystal Ship-The Doors (Season 2)
And none of these songs could be played with out the Metallicar.