Bard levels aren't useless for a fighter multiclass. Not only do they shore up all a fighter's weak saves, they also have some nice spells. Not all bards need to take wimpy charms and illusions. Haste, Bull's Strength, Cat's Grace, Endurance, Expeditious retreat (reckless charge) and Protection from Evil are all part of the Bard's repitore. The buff's can make up much of the difference between bard fighter and a straight fighter in single combat. Of course, if you were already getting buffed with those spells, the bard levels aren't as efficient. However, self sufficiency can be worth the loss of pure killing efficiency.
Around level 12, the fighter can pull one of the meanest tricks in the game. Convince the wizard to learn Antimagic Field and make an ioun stone of spell storing. You now have a nearly full proof defense against magical attacks. The stone can also be loaded with fun spells like heal or Tenser's Transformation. If the fighter has adamantine weapons and armor, he'll be at an advantage against most foes because he's prepared to deal with antimagic and they aren't.
Beg for Magic Circle against Evil. Not only does it protect against mind control attacks, it also gives a +2 deflection bonus and wards against demons.
At really high levels, the ring of spell turning becomes a clear winner. Almost all mind affecting spells are targeted, even the ones like confusion, so the ring can provide near perfect protection.