I've allowed fighters bonus special options at high levels like a rogue, something better than a feat. Many of these were plundered from this board, so thanks all around:
On attaining 10th level, and at every three levels thereafter (13th, 16th, and 19th), a fighter gains a special ability of his choice from among the following options.
Mettle: With mettle, a fighter can avoid even magical and unusual attacks with great strength of body. If he makes a successful Fortitude saving throw against an attack that has a reduced effect on a successful save, he instead takes no effect.
Weapon Master: A fighter with weapon master may spend shift his feats to match a different type of weapon to that he has trained with. He must spend one hour praticing with the new type of weapon, at which point the feats are changed. The applicable feats are Weapon Focus, Exotic Weapon Prof., Improved Critical, Weapon Specialization & Armor Specialization as well as all dependent feats such as Greater Armor Specialization.
For example, a weapon master with Weapon Focus (longsword) discoveres a magical battleaxe. He spends one hour praticing with the axe, after which he now Weapon Focus(battleaxe) instead of (longsword). This lasts until he again chooses to change the feat.
Master of Defense (Ex): The fighter has mastered defensive techniques that make him very difficult to harm when he goes on the defensive. When fighting defensively or using the Expertise feat, the guardian gains an additional +1 dodge bonus to AC, and the attack penalty he suffers may by switched to a penalty on all damage rolls. When taking the total defense action, the guardian gains a +2 dodge bonus to AC in addition to that granted by the total defense action itself. When the guardian uses a shield, or when they wield a weapon in their primary hand and another in their off-hand (or simply a double weapon held in two hands), they gain a +1 dodge bonus to AC.
Slippery Mind (Ex): This ability represents the fighter’s ability to wriggle free from magical effects that would otherwise control or compel him. If a fighter with slippery mind is affected by an enchantment spell or effect and fails his saving throw, he can attempt it again 1 round later at the same DC. He gets only this one extra chance to succeed on her saving throw.
Critical Accuracy (Ex): A fighter with this ability has develop greate skill at aiming their strikes against vital areas of their opponents, gaining a +4 bonus to rolls to confirm critical hits.
Pole-arm Mastery (Ex): A fighter with this ability may strike an opponent with the haft of a reach weapon. This allows him to threaten his normal threatened area as well as the reach of the weapon, a strike with the haft deals 1d6 damage (1d4 for meidum weapons). In addition the fighter ignores any cover provided by allies when wielding a reach weapon.
Tenacity (Ex): The fighter can stagger on through a potentially lethal blow to take less damage from it than he otherwise would. Once per day, when he would be reduced to 0 or fewer hit points by damage in combat (from a weapon or other blow, not a spell or special ability), the fighter can attempt to shrug off some of the damage. To use this ability, the fighter must attempt a Fortitude saving throw (DC = damage dealt). If the save succeeds, he takes only half damage from the blow; if it fails, he takes full damage. Since this effect would not normally allow a character to make a Reflex save for half damage, a fighter's mettle ability does not apply to the save.
Bonus feat: A fighter may select a feat instead of a special ability.
Also note the Armor Specialization and Greater Armor Specialization feats (+1 and +2 to AC with one type of armor, does not apply if denied dex bonus).
I've been thinking about allowing mettle at 5th for instance and make improved the special, but I'm still uncertian...
