Another drinking game I've played more than a few times is Flip Cup.
It's pretty simple ( as any drinking game should be ), and people get really competitive and loud ( also good ).
Flip cup is a team based drinking relay race. Two teams line up opposite of each other at a table. First person chugs their beer out of their keg cup. The next person can't go until the person before them has drank all their beer and set their cup on the edge of the table and successfully "flipped it" until it has landed upright.
We'll often play where you go down the row, then come back. So one person ends up going twice back to back, and the first person who drank will also be the anchor man.
Try it, it's fun!