Might as well weigh in on this one:

1. Complete lack of common sense and common courtesy. They're just not common anymore.

2. People who are completely oblivious to the world around them. Sorry pal, but the world does not revolve around you. So hang up the f***ing cell phone, turn off the f***ing iPod, and pay attention to where you're walking/driving/etc. I'm not gonna look out for your dumb ass, I'm too busy looking out for my own.

3. People who can't grasp that their actions have consequences.

More to follow at some point.