The only thing that I think might be overpowered that you've specifically mentioned is Power attack with a 2-handed sword.
We've looked at house ruling it to 1.5 times power attack with a 2-handed sword and 0.5 times with a light weapon (to make two weapon fighting more viable as well). While I think it's a reasonable house rule, we've just played it as written because it's not that broken, and a changed rule is another thing to remember.
Of the extra books, there's very little that's actually broken in the Complete series or PHBII, which are the extra player books that I'm familiar with. It seems fairly balanced to me.