Music is virtually essential for our group. It really adds to the feel of whatever situation the characters are in.
We entirely use soundtracks. LotR obviously is in there, but we use soundtracks from a myriad of different movies (Braveheart, Conan, The Mummy, Stargate, Waterworld, First Knight, Cutthroat Island, etc), anime (Escaflowne, Lodoss, Brain Powerd, Fatal Fury, Slayers, Evangelion, etc), and video games (Final Fantasy, Chrono Trigger/Cross, Xenogears/Saga, Suikoden, Grandia, Zelda, Dragon Warrior, etc).
We make sure that we use it at the appropriate times, so that it never gets repetitive (along with a 300-disc CD player).