I'm going to try something new here and try to think of some gaming moments that aren't in every thread of this kind... hmmm...
Allright, I'm going to add the ending revelations in Killer 7. I'm one of those mutants that could actually follow the story in that game and when everything came together in the end, it was like hearing a thunderclap in the back of my skull. Vastly underrated game.
Next, I suppose a more personal one, was when the GameCube first came out, or rather, Super Smash Bros. Melee. On a whim, I got it hooked up in my college dorm's big screen. In twenty minutes, we had twenty people surrounding that screen. We played tourneys for nearly 10 hours straight.
And most recently, although a bit trite, was first playing a 360. Now keep in mind, for the longest time I was a hardcore Nintendo fanboy. Didn't buy anything SEGA, Sony, Microsoft, Atari, nothing. After E3 2007 or whatever it was when Big N spent the entire time talking about Wii Fit, after spending years being dedicated for a handful of games and missing out on the rest, I finally threw my hands up, said, "Fuck It," and bought a 360. First game I played on a non Big-N console: Bioshock. Nice wake-up call, that was. Since then I've been backtracking and been picking up and playing all the games I missed out.