top three, probably:
the fact that people really hate us lately
the fact that we are destroying the environment and I worry that I will be living in a wasteland in 40 years when Sens. McCain, Clinton, and Obama will be dead or senile
the fact that torturing people is so incredibly stupid and inhuman and unamerican that it makes me want to slap people. it doesn't work, either. This is really the one, quite frankly, that is pretty make-or-break to me. The only time in my life I have gotten so mad that I started screaming at someone (and possibly used the word Fuck in class) was when this one guy tried to defend the use of torture. Although I have been a pussy about that other times.
I heard this one interview with a guy who was imprisoned in Guantanamo because he pissed off someone in government in some other country (Turkey), and he told his fellow prisoners "it's OK, we're being given to the Americans. They won't torture us. they're good, kind people. I've been to their country, and Americans treat everyone with dignity."
I also heard an interview where an Air Force officer who used to run some kind of interrogation unit in the 90s talked about how the methods being used in Iraq/gitmo/etc are ineffective, and we didn't even use them on Nazis in WWII because back then we knew they were so ineffective, and thought they were inhumane. We had a lot of success in WWII with getting captured Germans to talk by... treating them well and gaining their trust.
Both of those made me want to slap some people, and also cry for our country.