Was pondering some of the more well known tracks by bands that are played heavily on radio, yet were never released on single. Most obvious one is Led Zeppelin's "Stairway To Heaven", but the Eagles "Desperado", Billy Joel's "Captain Jack", Pink Floyd's "Comfortably Numb" and The Doors "The End" also come to mind as being instantly well known songs by bands that weren't released.
Just interested to hear some other's thoughts on popular band tracks never released on single.