You can attack from a prone position without penalty.
Prerequisites: Dex 15, Lightning Reflexes, base attack bonus +2.
Benefit: You can make an attack from the prone position and take no penalty on your attack roll. If your attack roll is successful, you may regain your feet immediately as a free action. Opponents gain no bonus on melee attacks against you while you are prone.
Special: A fighter may select Prone Attack as one of his fighter bonus feats.
Source: Complete Warrior, page 103.