Sega Genesis, but I like the newest one on the 360 too.
Also,
Timesplitters (PS2)
Warcraft 1&2 (PC)
Counter Strike 1.6 (PC)
Mario Kart/Party (N64)
Tony Hawk Pro Skater (PS1)
NBA Jam (GEN)
Wrestlemania (PS1)
Golden Eye (N64)
Mirrors Edge (360)
Wagers. When you're 13 and other 13 year olds think they're Gods they're willing to throw some money at it. When you're 16 and doing it, you (and them) tend to have a little more money to throw at it.
We're not talking a lot of money but it wasn't exactly a blue moon event for $500 from a LAN party lock in.