The NOT QUITE DEAD YET House Rule:
I have yet to actually implement this in a game, but tell me what you think:
If a blow is going to kill a character, i mean, the dice are rolled, the damage is done, the axe is about to drop, there's no frickin' way out of it...the DM asks the player, "Do you want death, or irrevocable maiming and damage and the chance you'll die anyway?"
This is a good opportunity to house rule events like dismemberment, such as when Vader cut Luke's hand off. Or permanent drops of 4 points Cha and Con as the player is mutilated, and never quite the same again as they hang onto a few threads of life. If nothing else it would be an interesting roleplaying scenario, and something a gaming group would never forget.