I have a large collection of post-rock and similar instrumental songs that I frequently listen to while working. Spotify has a great selection of songs on a curated playlist called "Deep Focus". Having something playing that I'm not going to focus on really helps me get in the zone and focus on what I need to get done.

Also, sometimes I'll listen to Coffitivity instead--times that I'm looking for some background noise but I'm tired of the usual playlists. It's a looped recording of various public places. Eventually you get to notice the loops, but its still pretty solid.