I remember seeing an article back in the 90s or maybe even 80s that was exploring the possibility of the entire passenger compartment separating from the wings and rest of the fuselage and parachuting down in the event of a major failure. The thing is, it would be ridiculously expensive to implement, and there are very few situations where such a system would be any better than keeping the plane in one piece.
Except if you go far enough left, you get your guns back...