Bungie have a
section on their help
pages that explains their RSS feeds for player stats. If you've not started tinkering, that'll probably be your first
stop.
Now then, Carnage Stats can do all sorts of cool things with your RSS stats feed. Break them down so you can see what
maps you do well on, what weapons you're useless with etc… It's a great site for you online Halo 2 fans. It even has
leaderboards detailing various categories.
There's also a handy page here of Halo 2 related
stats tools.
Engadget
TUAW