Here are a couple of rulings I've made in my DF game. And naturally, rulings become rules by repeated use, and I expect to keep using these.
Attacking Crippled Limbs. If you strike an already-crippled limb, you can't do additional HP damage to the target. But you do cause shock penalties normally, and dismemberment works normally. Attempts to use grappling to inflict pain (Technical Grappling, p. 38) work normally, as well.
I will apply a penalty to the HT roll to determine severity of a crippled limb (p. B422) as well if there are repeated strikes to the same limb. Such a penalty generally is in the -1 to -3 range, sometimes more.
Why? A crippled limb isn't a numb limb that's immune to damage. One that has been dismembered is, so if a berserk animal has your crippled hand in its mouth chopping it off at the wrist so you can escape and stop suffering pain and shock is a valid tactic. Not a long-term good tactic, unless it keeps you from dying. Also, this means if you arm lock someone and break the limb, they don't suddenly become immune to pain compliance. In fact, they're worse off . . .
Resisting non-Resisted spells. What if you throw a utility spell on a hostile opponent for some nasty effect? For example, Purify Air on a hostile air creature, or Minor Healing on a Nilbog, or Phase Other on a foe being touched by his own ally for a touch-based buff spell. It's resisted by the better of Will or HT. Spells that don't come with a native resistance are assumed to be poor at overcoming resistance and so targets get to choose their better resistance to stop it. Creatures who automatically take damage from certain effects may not get a resistance roll, but the default is allowing a resistance roll.
Why? Because it's not addressed in the rules, and it's clearly a case that should be. Turning utility spells into attack spells that bypass the rules for attack spells isn't really fair, it's trying to bypass fair. And yes, you can resist Great Haste, so your enemies can't toss that on you while in Ethereal Body and wait until you run down to -FP and pass out. Not allowing resistance is allowing clever loophole-hunting instead of clever play.