"I hear the Man a-comin' / He's rolling 'round the bend - on 104 tracks!" Or so you'll sing in praise of the Man in Black's big boxed set, The Legend (Columbia/Legacy). His name, of course, is Johnny Cash, and the box serves up four CDs of songs that include seven previously unreleased performances.
If you're the sort of person who enjoys watching classic concert films and music documentaries (and let's face it, you're reading Sound+Vision, so I'm pretty sure you are), you probably wouldn't mind having access to a big archive if such things, available from wherever you are on almost any device.