I have to listen to music when I study. I catch myself listening to the same thing for different subjects, and I have even posted about these habits in the past. This semester I am taking my first Hebrew class and a pretty intensive exegesis class on the general epistles. Both of these involve alot of language work and memorization, this means I will try to find either really complicated stuff to listen to or something very repetitive. My usual go-to's are Radiohead and Wilco, although Low got some serious listen time last year and I figure that some new things might creep in. I wrote my entire doctrine notebook to Godspeed You Black Emperor! and it seemed to be a good fit. If you check out my last.fm widget on the side of the page you can see what is getting playtime.
So what do you listen to when you study?