After my players were on the short end of a total party kill I've decided to codify the optional rules I'm going to allow them to draw upon during gameplay.
Shields Shall Be Splintered: A character wielding a shield may elect to have the shield be destroyed in order to avoid being struck by a killing blow. Magical shields are knocked out of the character's hand and a full-round action must be spent to pick it up again.
Helmets Shall Be Dented: A character wearing a helmet may elect to have the helmet ruined in order to avoid suffering a critical hit. This reduces all damage done to 1 point. Magical helmets are knocked off a character's head and a full-round action must be spent picking it up and putting it back on.
Feel The Burn: I know I read this elsewhere but currently can't find the source. A character may take a permanent 1 point loss in Stamina to heal 1 hit dice worth of hit points. If the reduction in Stamina results in a penalty (or a loss of a bonus), the maximum hit point total of the character is affected.
Coup de Grace: As long as a creature has the discernible anatomy for a coup de grace, it may be performed on their defenseless body. Prone but active targets still require a roll to hit.
Perception is not a Skill: Perception rolls become a function of the relevant ability plus level added to the roll. (see Method 3 in the link)
Take Ten: If the character is not in combat (or a stressful environment) they may avoid rolling a die to accomplish a task and instead may "take ten" minutes to finish a task. The task is finished as if they rolled a '10' on their die. If they succeed they may continue on, if they fail than they must accept the result. This rule may be used to carefully cast a spell, climb a ledge, or examine their surroundings. (There is NO 'Take Twenty' rule.)