To keep my spirits up in the most boring times in front of the easel, I often listen to audiobooks and podcasts. Now a days I listen to a lot of podcasts from BBC Radio 4, espescially In Our Time, where they discuss topics on science, history, philosophy, religion and culture. I started out listening mostly to history, but have switched more to science and philopsophy at the moment. It's fascinating stuff, and I learn so much while I'm drawing. (I love multitasking!) I can't help but smile whenever they talk about one of the philosophers mentioned in The Philosophers song by Monty Python though. That is after all where I heard most of these names for the first time! :)
Another podcast favorite is No Such Thing As A Fish, filled with fun and bizarre facts.
I sometimes listen to music, and sometimes work in complete silence, but I usually listen to something because time just flies by that way!