I appear to be the only person massively in love with "So What." It didn't hook me till I saw the video; whether this is because I just needed to listen to it more than once, or because it is actually not a good song without the video, I'm not sure. (But I managed to listen to it six times in a row before I realized how lame that looked on my Last.fm page, so I'm guessing it's the former.)

And according to Wikipedia, it's Max Martin.