Posterous: A blogging site shutting down April 30. IRC Channel #preposterus. Currently has the most attention.
Yahoo! Messages: Message boards on Yahoo! shutting down April 1st. IRC Channel #BurnTheMessenger.
Opensolaris: Shutting down March 23. IRC Channel #ClosedSolaris.
Gamespy, 1up, UGO, IGN: Shutdown date unknown, announced Feb 21, 2013. IRC Channel #ispygames.
Formspring: Announced March 15, shutting down March 31st. IRC Channel #firespring
We have an online tracker that lists currently running warrior projects.