The best that come to mind are Nick Naylor's bribe to the Original Marlboro Man, where he gives him advice on how to really put the screws to Big Tobacco by requesting a specific interviewer, dumping the "blood money" on the floor, and loudly declare that not only will they not shut him up, but he'll establish a charity with their attempted bribe. However, seeing that much money laying in front of him when his ranch is in dire need of fixing up and he's got bills to pay changes the Marlboro Man's mind, and Nick knew it as soon as he started on his spiel.
Nick's final speech on the freedom to choose:
Gentlemen, it's called education. It doesn't come off the side of a cigarette carton. It comes from our teachers, and more importantly our parents. It is the job of every parent to warn their children of all the dangers of the world, including cigarettes, so that one day when they get older they can choose for themselves. I look at my son who was kind enough to come with me today, and I can't help but think that I am responsible for his growth and his development. And I'm proud of that.
Maybe it's just me but Nick answering the senator's question about whether he'd be fine with his own son smoking:
"If he really wants a cigarette, I'll buy him his first pack."
That just...that takes guts there, to say what would probably be an unpopular answer.
This was also treated as a Crowning Moment of Awesome within the film itself, as Nick's emphasis on personal choice was enough to sway public opinion in the cigarette company's favor on that particular issue.
Even the very first thing he does in that hearing is awesome. When asked point-blank if he thinks smoking is dangerous, Nick replies with a Flat Yes, and goes on to state that he would find it incredible to find someone who thinks smoking isn't harmful to one's health, completely undercutting the entire point of the hearing: put a skull-and-crossbones mark on all packs of cigarettes to discourage people from buying them. With all the attempts by Big Tobacco in the film to downplay the dangers of smoking, fully admitting the dangers and still beating the opposition is quite impressive.
"I'm his father... You're the guy f***ing his Mom."
Turning the Littlest Cancer Patient act onto the anti-smoking people on a talk show, by claiming that the anti-smoking groups want him dead, while the tobacco companies don't want to lose a valuable customer. The Captain himself was very impressed.