Improved shield bash is quickly becoming my favorite feat.
A multiclass ranger/fighter.
Feats: Shield Expert. Power Attack. Improved Shield Bash. Weapon Focus (Longspear). Monkey grip (longspear).
Opponent approaches. AoO. Your turn. Shield bash. Hit. Push them back 5'. All your allies standing next to you get AoO's. Stab them with your longspear. Take a 5' step back. Opponent is now 10 feet away. Lather, Rinse, repeat.
Mix in knockdown, and your shiled bash attack may be able to knock them down (especially with power attack). Then you push them back 5', and knock them down. Then stab them with the spear where it hurts.
You're almost equally a Large and in Charge critter.
Mmmmm.