Moments ago, we watched the odometer of Halo 2 players roll over the 5,000,000 mark. Today also happens to be the 2.5-year anniversary of launch. Here's to continued growth of 2 million players per year!
If you're curious, "ultra theodore" is the 5 millionth player.
(This number refers to the number of unique Live accounts that have played Halo 2 online, not including guests)
Edit - I also just noticed that we're a few hours away from 700 million unique multiplayer games on Live. (The largest number, player-games, where each game counts once per player in it, will hit 5 billion in a few weeks)