So, are you using the Dungeoncrasher variant from Dungeonscape? If not...you should if you can.
I had a similar character before, except it was a Barbarian/Rogue, using the rogue variant that gets fighter feats instead of sneak attack.
Good feats: Power Attack, Imp. Bull Rush, Knockback, Shock Trooper If enemies charge a lot, adding Cometary Collision to the above results in some hilarity.
I was looking at rogue in fairness and using a large great flail (how awesome!) with trips and disarms and sneak attacks, but figured take more feats that can use the powerful build side! What does shock trooper do?
Heh, my Goliath used a Heavy Flail and did all that fancy stuff (disarm not so much, though).
The Shock Trooper feat enables the use of three tactical maneuvers.
Directed Bull Rush: To use this maneuver, you must make a successful bull rush attempt as part of a charge. For every square you push your foe back, you may also push that foe one square to the left or right.
Domino Rush: To use this maneuver, you must make a successful bull rush attempt that forces a foe into the same square as another foe. You may make a free trip attempt against both foes at the same time, and neither foe gets a chance to trip you if your attempt fails.
Heedless Charge: To use this maneuver, you must charge and make the attack at the end of the charge using your Power Attack feat. The penalty you take on your attack roll must be -5 or worse. In addition to normal charge modifiers (which give you a -2 penalty to AC and a +2 bonus on the attack roll), you can assign any portion of the attack roll penalty from Power Attack to your Armor Class instead, up to a maximum equal to your base attack bonus.
Most take it for Heedless Charge, but the other two tactics are a gold mine for bull rushers as well. You do have to wait till you have BAB +6 for it, though.