I just saw this in the Seattle PI today.
"Microsoft Notebook: Tool connects 'Halo 2' with ... Excel?"
Using the RSS feed that http://www.bungie.net provides, Microsoft Excel Program Manager Sam Radakovitz was able to create a better way to check out your Halo 2 stats. (Well, the Game Viewer is pretty darn cool as well).
Per game, you see displayed in Pie Graph form how much you contributed to your team in Score, Kills, and my best category, Deaths.
You can also check out Kills per Map, Kills per Game Type, etc.
Try it yourself!