YouTube tracks the music videos that you click on, and then builds mixes based on this information. It’s actually quite good.
Note: You can neither copy the ‘mix link’ nor can you forward it, which is unfortunate.
My current favorite mix is based in part upon the following (none of which are spoiled with commercials / at least not as of this moment):
Great Compassion Mantra Song
Kuan Yin Crystal Music
Crystal Music for Meditation
Chinese Bamboo Flute