The Rock & Roll Hall of Fame recently released a list of the "Definitive 200" albums that should be in everyone's collection.
Here's the site:
http://www.definitive200.com/200_list.php
Here's the entire list in PDF:
http://www.narm.com/D200/D200MasterList.pdf
Here's Google's
HTML version
For those who don't want to click, here's the top 10:
1 Beatles, Sgt Peppers
2 Pink Floyd, Dark Side of the Moon
3 Michael Jackson, Thriller
4 Led Zeppelin IV
5 U2, Joshua Tree
6 Rolling Stones, Exile on Main Street
7 Carole King, Tapestry
8 Bob Dylan, Highway 61 Revisited
9 Beach Boys, Pet Sounds
10 Nirvana, Nevermind