Now it seems the recording industry's doing it as a gimmick to sell albums. I wouldn't pay too much attention to their list, it makes little sense (except, as Salon notes, from a marketing standpoint). I'll join in the fun here, though, and I suggest you do, too.
First, a note about my hermeneutic. What factors should we use to evaluate albums: sales, influence, proportion of good tracks to filler, or stuff that just plain RAWKS? Obviously, many factors should be weighed, though I personally am going to give influence on later music a position of primacy, followed by "rockin'"-ness, then the other stuff. I'm also going to stick to rock, for fear of venturing too far out of my element.
1. The Beatles' White album
2. Bob Dylan's The Freewheelin' Bob Dylan
3. The Jimi Hendrix Experience's Electric Ladyland
4. The Sex Pistols' Nevermind the Bollocks
5. Grateful Dead's American Beauty
7. Pink Floyd's Wish You Were Here
8. U2's The Joshua Tree
9. Cream's Disraeli Gears
10. Nirvana's Nevermind
I've obviously missed glam rock entirely, and that did take up the better part of a decade's worth of rock, but I feel that, for one, it was a shitty era with no one worth replacing any of the albums above, and for two, the things worth remembering and that were worth passing along from glam were borrowed from Hendrix, Floyd, and Cream.
As with any list, there were albums I wanted to add but couldn't, so here's a quick and dirty 11-20, in the order I thought of them:
11. Tool, Anima
12. Metallica, Master of Puppets
13. Elvis Presley, self-titled
14. Bruce Springsteen, Born to Run
15. The Doors, self-titled
16. The Rolling Stones, Sticky Fingers
17. Led Zeppelin, IV
18. R.E.M., Green
19. The Pixies, Doolittle
20. fine, Bon Jovi, Slippery When Suck