In 2004, before the release of Halo 2, a website separate from Bungie.net, Halo2.com, went live, with information about the units, vehicles, and weapons in the game, laid out as if from the perspective of a Covenant intelligence agency. Similarly, Halo3.com launched late last month, largely from the perspective of UNSC intelligence-gathering, with information on Halo 3.
However, the site is Flash-based. You can't search it, and you can't comment on it. So I've transcribed the content, added commentary and a keyword searching mechanism, and used it as the basis for the Halo 3 Guide, similar to 2004's Halo 2 Guide.
Please feel free to comment on any of the items!