Well, there are such titles as Rookie, Tilted, Crazy, Junkie... Those are automatic. Once you get to a certian point, you can make up your own title. People get to show their personality a bit more through that.
Supermod's and moderators are the boss of you
Basically they keep us all in line.
You might also notice that it says "Donor" under some folks names. This just means that they have donated to the site.