I know of some others but they are closed-circle sede boards. Opposite approach from Matthew. Which I agree with for the most part, since SSPX breeds some aggressive people like Caminus who seem to trying to enrage sedes.
This site is the only place where the SSPXers and sedes can mix relatively peacefully. I have thought about it and realized that it is knowledge of cօռspιʀαcιҽs, Jєωs, etc. that is the glue of CathInfo, because not all sedes are like that ( especially at CMRI where there is some naive patriotism, to put it charitably ).