American used to have it, years ago, but eliminated it when a pilot found a lawyer on board taping it, just in case, or so I'm told. (Why this would be an issue is beyond me, since anyone on the ground can do the same thing to their heart's content.)

Currently only on United; Channel 9 on all aircraft with audio ent. systems; Can be cut off by Captain (and is, all too often); When cut off, is replaced, depending on aircraft, either with nothing or with Hawaiian melodies.