Got two I haven't seen mentioned yet.
Procol Harum: A Whiter Shade of Pale
Steppenwolf: The Wall (off of Rise and Shine)
While the first tune is well known, I bet some of you haven't heard the latter tune. It was a song from 1990 written about the Berlin Wall. A very heartfelt tune by John Kay about the wall coming down. If it is anywhere on YouTube, though, I can't find it. Otherwise I'd have posted a clip.