Best background tunes for command line "kung foo" (solving deeper problems on the command line)

For those who use the CLI a lot… when you have some deeper problem that you are digging into (and you find yourself deep into shell “kung foo” territory), and you are feeling like some appropriate background tunes (that don’t really occupy your mind, but sort of set a pace for your work, and keep you feeling motivated, and in a good mood), what do you put on?

For example, here’s one I put on recently (some “Drum and Bass” Electronic music, which is OK once in a long while), as I debugged a challenging ruby shell-environement-related problem (that took me a good hour to solve):