Improved Sunder, if used judiciously, is a great feat. Use it to destroy a mook's mundane weapon, rendering him ineffective in combat. Use it against annoying archers. If you take the tactical feat Combat Brute (from Complete Warrior), you get a cleave-effect after you sunder something. So you can destroy the archer's bow and also smack him.
Do not use Improved Sunder on the shiny magical sword you intend to take as your loot.
The combat action bull rush is not useless. For example, if a monster is threatening a spellcaster, a friendly fighter can bull rush the monster out of the way. Yeah, he provokes an AoO, but better the fighter than the spellcaster. (Of course if you have Improved Bull Rush you don't provoke the AoO.) You can also bull rush enemies into being flanked, bull rush them off cliffs, bull rush them into pools of lava, bull rush them into rough terrain where they move slower, etc.
If you're just standing on the battle grid hacking away, you are fighting dumb. Use tactics! Move around! Cooperate!