Codex
Hmm. Looks like Mongoose's Classic Play: Book of the Planes is getting put on the Grand OGL Wiki. There's a lot of interesting stuff in that book . . . and perhaps most usefully for the Codex project, a Deep Ethereal with elemental Border Ethereals. Hope it makes it into the wiki.
(The existing Open Content declaration on the Book of the Planes is a lot more limited, at least at first glance, than what's apparently getting put into the OGL Wiki. That's why I avoided the Book of the Planes material as a source. Since the Grand OGL Wiki was created at Mongoose's initiative, though, I trust anything of theirs that gets on the wiki is fair game.)
(The existing Open Content declaration on the Book of the Planes is a lot more limited, at least at first glance, than what's apparently getting put into the OGL Wiki. That's why I avoided the Book of the Planes material as a source. Since the Grand OGL Wiki was created at Mongoose's initiative, though, I trust anything of theirs that gets on the wiki is fair game.)