Back in my college years, my roommates and I would play LAN games every night and weekend. Age of Empires, Starcraft, Netstorm, Quake(1 or 2), Age of Wonders, Allegiance, etc. Most of the time we played cooperatively, and really slaughtered the computer enemies.
For example, in Starcraft, I would play human, one guy would play Protoss, and another had Zerg. The Protoss guy would set up a defense perimeter for all of us, the Zerg would kick out thousands of infantry, and the Protoss would work on the monstrous battleship-thingy. Eventually, he would take one of my builders and build some firebats too. Then, we'd all charge in (usually against a Zerg), and slaughter them in no time flat.