You can choose to do nonlethal damage with just about any attack if you take a -4 on your attack roll.
Monk Unarmed Strikes can do lethal or nonlethal at the Monks' discretion.
There are Feats you can take that will let you do nonlethal damage. Bludgeoner comes to mind. Claws, Bites, Tails, Hooves, and Tentacles all do Bludgeoning Damage, iirc.
I there is the Merciful weapon enchantment. You could get that on an Amulet of Mighty Fists.