The Myth Vault Forums
Update: Achronos has informed me that the Myth Vault Forums will not be coming back. The traffic there died out months ago, so there is not much of a need for them any longer, especially with the spiffy new bungie.net forum system.
-Big Bad Biker Momma
I know this isn't used much, but the server running the Myth Vault open source development forum is offline. It is being worked on, but I have no ETA. So, in case you were wondering, that's why you can't get to the Myth Vault forum.