A friend on Facebook just asked "List 10 albums that made a lasting impression on you as a TEENAGER, but only one per band/artist." A few from this friend:
4. Atrium Musicae de Madrid - Musique de la Grèce antique
5. Jean-Michel Jarre - Oxygène
6. David Munrow - Instruments of the Middle Ages and Renaissance
7. Pink Floyd - Meddle
8. The Balinese Gamelan: Music From The Morning Of The World
My most influential/most constantly listened to (from my first album at age 11 in 1976 to when I was a freshman in college in 1983) were more mundane:
Bay City Rollers "Dedication"
KISS "Double Platinum"
Cheap Trick "Live at Budokan"
Beatles "Rubber Soul"
John Lennon/Plastic Ono Band
Go-Gos "Beauty and the Beat"
The Knack "Get the Knack"
Paul McCartney "Tug of War"
Prince "Purple Rain"
I still listen to all of these today.