All of the discs I was going to mention have already been mentioned in this thread (YHF, Being There, OK Computer, The Bends, Mutations, White Blood Cells, etc.). But there are two notable exceptions:

1. Built to Spill - Ancient Melodies of the Future
This is a great collection of songs, and a fabulously cohesive album for me. But a classic isn't really a CLASSIC until it goes out there and reaches for that moment of glory. This disc does that on track 8 (You Are), abandoning its powerfully hooky song structures for a transcendent, explosive swirl of guitar and emotion. It either works for you or it doesn't. It does for me.

2. The Notwist - Neon Golden
The sound of world-weariness has never sounded so beautiful, so wistful, so fragile, and yet so powerful. Who was it that said writing about music was like dancing about architecture? Now I know what he meant.

Oh...and an honorable mention to REM's overlooked, underappreciated New Adventures in Hi-Fi.