The frequency with which I find myself posting is erratic at best, not adhering to any schedule but only when the muse strikes. This is a trait that defines my writing habits in general, in fact. But lightning can apparently strike twice in the same week.
I find that when I'm running a game (or writing), I like mood music. Something instrumental usually, and intended to evoke a certain sense of ambiance. While there are many options out there, ranging from classical to jazz, I'm partial to film scores.
For classic fantasy, the sweeping orchestral scores of film can be handy. The LotR scores are perfect, though I'm sure that most of the nerds in your game will recognize it. The same can be said for the Star Wars scores. But there are others that can be good if used appropriately, and are less recognizable.
I have my laptop loaded up with scores from film, television and video games, as well as some of my favorite classical composers and jazz musicians. I like to be able to pull up a track that will fit the scene, whether they are in a pub, a dance club or a sterile office building. Vigorous music for combat can help liven the pace and ease the distraction during lengthy combat sequences.
Where do my fellow gamers/GMs weigh in on the music subject?