10. Threatening an area while unarmed. (Do you or don't you?)
My Best Advice: You don’t threaten an area or get attacks of opportunity if unarmed, unless you are a monk or have the Improved Unarmed Attack feat.
The Rules: You "threaten the area into which you can make a melee attack." (PHB p. 122). On table 8-1, "Attack (unarmed)" is a separate entry from "Attack (melee)." On p. 140, "striking for damage with a punches, kicks, and head butts is like attacking with a weapon, except for the following." Lack of threatening the area around is not listed here, or anywhere else in the rules.
The Sage: You don't threaten while unarmed unless you're "considered armed" (have Improved Unarmed Strike, are a monk, are a monster using 'natural weapons,' etc.)
Other WotC/former WotC opinions:
Argument For: It complicates combat, because then an archer might threaten the area around him with "kicks" and "head butts" which is just wrong. The rules are not clear on this as the "Argument Against" would suggest - otherwise this debate would not exist.
Argument Against: It's the rules and the Sage is off-base. Unarmed attacks are pretty wimpy anyway since they usually provoke AoOs and do tiny damage--so most people won't take them. Some AoO actions like "trip" or "grapple" are basically unarmed actions; it makes no sense that a holding a crossbow bolt in your off-hand would allow you to make grappling attempts and trips as AoOs, which you couldn't do unarmed. The book clearly states that you threaten an area whenever you can make a melee attack. Having an armed attack (such as a Melee Attack, an Improved Unarmed Strike, or a Touch Attack) or an unarmed attack (Unarmed Strike) is irrelevant. These are all melee attack forms.