Presurfer points to a nifty site called Songfacts. I played around for a while on it and its great. Type in some of your favorite songs to learn more additional facts, they dont cover everything of course but its rather thorough.
“Songfacts is a searchable database of song information compiled by radio professionals, music enthusiasts, and visitors to this web site. We hope using this site will help you better understand and enjoy the songs you listen to, and invite you to share your knowledge with us so that others may benefit.”