A couple of tiny but very convenient items I travel with (often in addition to a headset):

Radio Shack Volume Control Cable for Stereo Headphones Model # 42-2559 ($6.59.) (Actually an inline variable attenuator, which allows me to lower the AA QC2 headset volume to background listening status; AA has had the original QC2s "specialled" so the volume control, set to "high," is inaccessible as it is cemented into the plug receptacle. Try to lower the volume to background, the audio will cut off.)

When I travel with Lady JDiver, I add a "wye" connector so if either person's audio out jack is bad, we can literally split our listening in the worst case scenario.