Yo-Yo Ma - Bach, Cello Suites. Because it played a big part in a West Wing episode years ago. And I just heard it again on House. Also years ago in real time but just yesterday to me. And it's really great.
Mischa Maisky playing Bach's 1st Unaccompanied Cello Suite. This was the first CD I ever bought...and when I played it on my new system, I could not believe the sound. Opinions may differ on some things, but to me this is just magnificent.