Ambient seems to work best for me. More generally speaking, calm, instrumental music (i.e. no vocals), which includes some jazz-y music as well (In A Silent Way

Ambient seems to work best for me. More generally speaking, calm, instrumental music (i.e. no vocals), which includes some jazz-y music as well (In A Silent Way by Miles Davis, or Sunset Mission by Bohren & Der Club of Gore, to name two). If that is up your alley, I can recommend the following artists: Boards of Canada come to mind. Carbon Based Lifeforms (especially their album "Twenty Three"). Marconi Union. Steve Roach made some pretty awesome stuff (Structures From Silence especially). Every now and then - rarely, actually, but that is not a statement - I will get out the Cocteau Twins. There are lots of vocals, of course, but rarely anything resembling lyrics, so that works for me. Also, some of the stuff Dead Can Dance made before they split up was pretty great. Towards the Within and Spiritchaser were quite great.