Often I will listen to movie tracks, or techno-like stuff, or classic rock. Have them on in the background, and might even listen to single songs or whole albums on repeat. They act as a way to fill up the void in my brain which might otherwise be filled with distracting chaff, and some surprisingly inspired ideas pop up when listening to some kinds of music.
I think my most recent idea came to me on a night time walk while listening to ACDC's Thunderstruck... Back in Black might have had some influence in there as well, along with Spoiling for a Fight. I usually skip through albums until a track catches my fancy. Then I run with it like it's a pair of scissors.