LFG Armory is a new site that's aiming to beat the official Armory at its own game. Blizzard's site, as complete as it is, is still occasionally buggy and slow, and LFG Armory is looking to give players an alternative. And it works fairly well -- while the FAQ claims that data may be a little behind (due to caching of Blizzard's information), both the guild and player profile pages look pretty good and load quickly (and if the site can stay up after we link to them here, that'll be a real sign that it's a stable server).
But the real feature that makes LFG Armory something more than Blizzard's official site is that it has a guild and arena team matching system built in. Once you register your name and your characters, you can do a search for guilds and arena teams and try to find one that matches what you want -- percentage of level 70s, class makeup, and number of members. On the guild side, you can set your guild as looking, and then when you hit a match, LFG will match you up.
It's an interesting system, but like all social networks, it all depends on participation -- when I looked for a guild for my Hunter on Cenarius (who could use a guild, by the way), nothing came up, because likely no one on the server was looking (for a Hunter at least). But as an alternative to the Armory, LFG is looking pretty good. If they can get people to the site and stay up, they might give Blizzard's official site a run for its money.
[Via World of Raids]