This may be old news, but... anyone thought of using this combo?
[General](DR317 p82)
Prereqs: Base Attack Bonus +6, Strength 13, Iron Will, Power Attack
Once per round as a Free Action, you may sacrifice up to your Character Level in hit-points (treat this as lethal damage that bypasses Damage Reduction). For the 1 round, you receive +N bonus on Attack and Damage, where N equals (hp sacrificed / 2).
Stone Power
When attacking, full attacking, or using a Stone Dragon maneuver, you can subtract up to -5 from your attack and gain 2x that number of temporary hit points which last until your next turn. It also counts as Power Attack for prereqs.
So... you could take 5 off your attack and gain 10 THP with Stone Power, then sacrifice 10 HP from Lady's Gambit to receive a +5 to hit (negating the penalty you took) and +5 to damage.
Since you can buy Iron Will for 3,000 gp, and Stone Power counts as Power Attack for prereqs, you really only need to take this one feat for +5 to damage. Right? That's not stupendous, but it is decent.