How about this one - jasmasson's Whatever You Say (http://community.livejournal.com/rounds_of_kink/27315.html?style=mine), where Sam's been hit with a magic spell that makes him want to obey.

There's merepersiflage's Pushed Buttons, Crossed Wires (http://merepersiflage.livejournal.com/1591.html?style=mine) - Dean has to punish Sam for being careless.

And if you like underage, sheaseth99 has this spanking one (http://community.livejournal.com/roseblue24/5551.html?style=mine) that is very very hot.