I am going to have to go with something that is not yet on the list.

Paintball

This is such an exciting and up and coming sport, albeit a bit expensive to participate in.

Seeing XBall Tournaments or simply 5v5 team capture the flag games can get quite interesting.

I suggest you check it out to watch sometime if you have the chance to.

-Litos
Stephen Fry on "respect" and being "offended".
Calgon take me away.