This has probably been covered but what is the music playing in the Dude's headphones at the doctor's office?
I take it to be Elvis Costello.
My Mood Swings, by a great musical hero of mine, Elvis Costello, indeed!
It's not on any album I own, not sure if it was perhaps specially made for the movie, perhaps as a favour to T-Bone Burnett.
Perhaps worth me investigating at some point.