Since this thread is repeating itself a bit, I'll take a slightly different approach: I ban the Dodge feat.
Usually banned rules involve ideas like "this is too powerful" or "I don't trust my players", but banning Dodge is different. Dodge gets in the way. The Dodge feat adds +1 ac, a practically irrelevant modifier, and it adds it to only one enemy, which means more bookkeeping. Furthermore, it is a prerequisite for other, more interesting rules (and I don't mean Mobility, I ban that too), which I say you can get without the banned prerequisites, thus freeing the players to more fun choices, even if that means they become more powerful.
I don't ban sourcebooks, even ones I don't know, because I trust that anybody playing with me would be able to apply discretion and common sense rather than legalism and competitiveness in a co-operative game. I don't even ban third party sourcebooks, which sometimes have neat ideas that haven't been seen before in any actual games because people are so quick to disregard them for being third party.
In conclusion: I believe the game is about fun, and building characters is part of it. I strongly believe that the players can be trusted to know the rules for their own character better than I do, so long as it lets their character interact with a game in a fun way. It shouldn't be an antagonistic relationship, with the DM providing the rules and the players trying to make the most powerful thing possible within it. Ideally, the limits on a character should be placed by the players themselves.
Here comes the fine print: no, I'm actually not that free-wheeling, and lots of things are vetoed for being overpowered or for getting in the way of the fun of other players. But its the thought that counts.