I just wanted to confirm something about threatening opportunity attacks:
Let's say you have a character who is wielding a 2-handed polearm with reach and who also has the Improved Unarmed Strike feat. Am I correct in assuming that, in the absence of special feats or class features, his options at the end of his turn are to either keep both hands on the polearm and thus threaten foes who are 10' away but not those who are adjacent, or remove one hand from the polearm so that he threatens adjacent foes but not those who are 10' away? Or would the free action to change grip on the polearm so as to threaten both ways be allowed as part of an opportunity attack? Or, since unarmed strikes do not have to be made with the hands, would he be allowed to kick adjacent foes?
I have a rather easygoing GM who could probably be persuaded to go either way on this question, but I would prefer to start with the rules legal "correct" approach.
As long as your unarmed strike (any part of your body) can do lethal damage normally (be considered armed) then you will threaten your natural reach, which is normally to what is adjacent to you.
Specifically, a medium sized creature holding a reach weapon, and has IUS could reach 10 ft with the reach weapon to threaten all those squares, and the IUS would threaten the 5 ft reach. This would continue to happen even for when it is not your turn, such as AoO's.