I keep listening to Johnny Cash's rendition of the Nine Inch Nail's song "Hurt." Only The Man In Black could make a Trent Reznor song that much darker.
The video, which has been said to have reduced both Zackl De La Rocha (ex-RATM frontman, for those not up to date with their RATM history) and Trent Reznor to tears, was directed by Mark Romanek. It's probably the most powerful and profound music music video I've ever seen. (Well, with the potential exception of Motley Crue's "Girls, Girls, Girls." That kind of late 80's art & emotion is hard to top.) Johnny Cash may be old and sick these days, but he's still the motherfuckin' Man. And this video is a touching, realistic tribute to him.
If you care to, you can read more about the Hurt video here.