Can you get a Necklace of Natural Attacks (swarm attack) and choose sizing?
I remember going over this one on another thread. I'll sum it up here.
Normally an unarmed strike isn't considered a weapon capable of being the target of such an effect, however, the monk's version of unarmed combat specificially states that his unarmed strike can be considered a weapon for the target of such effects. So, make sure you are a monk to try this sort of thing.
Getting sizing in your hands is a little difficult, but not impossible. The kensi PrC jumps to mind. The artificer weapon augmentation infusion is another.
Once you have sizing, you run into a little problem involving what happens when you change the size of your hands. See, unarmed strikes are considered light weapons. So, once you add sizing, you can change the size, but not more then one size up, and you can't shrink them.
When you go up a size,you gain a -2 to hit and it becomes a one handed weapon. You go up a second size and now your hands are two handed weapons. Well, how do you wield TWO, two handed weapons? You can't. (Strange feats aside.) You can't unequip your hands. So when you go the second size, your hands become too big to do anything and remember that a monk's feet and knees and elbows are all considered valid methods of attacking, so all of them go up in size as well. (Which is just a funny image, as far as I'm concerned)
You may have multiple methods to inflict your unarmed strike, but you only have one unarmed strike. Put a WSA on it, you put it on all of them.
Also, you can't wield a weapon that is too small. So if you shrink your hands, you can't attack at all. Although you can certainly lie on the side of the road and beg for money. A man with shriveled hands, feet, knees and elbows could certainly pass for a cripple. Maybe it could even pass as a cover story for an assassin. (How could I have killed the king? Look at my limbs!" *Wiggles his diminuative toes*)
The only reason I can see for ever using this is so you can increase your hands to one-handed weapons so you can choose to two-hand wield your hands and then perform a power attack for x1.5 damage.