All of the Calm# and Piano# songs in minecraft! I usually go to sleep with those songs, they're amazing, soft, relaxed songs. Other (long list xD) songs that are relaxing to me as well:
Alizee - Par Les Paupières
Vampire Weekend - Mansard Roof
Moving Units - Anyone
The Beatles - I Will
The Beatles - In My Life
Animusic - Harmonic Voltage
Gorillaz - La Manana
Daft Punk - Something About Us
Daft Punk - Veridis Quo
So, so very fitting. As with most really good things, though, Judas ruins it.
My DeviantArt
I'm not a man. I'm not a man at all.
Alizee - Par Les Paupières
Vampire Weekend - Mansard Roof
Moving Units - Anyone
The Beatles - I Will
The Beatles - In My Life
Animusic - Harmonic Voltage
Gorillaz - La Manana
Daft Punk - Something About Us
Daft Punk - Veridis Quo
Here's some meditation music.