For young adult psychics who specialize in astral projection, dreams and meditation: Astral Society
It's a very small forum, not too active, and it has a few boards for real life issues but it's very casual about personal development. That aspect is more of a peer support thing.
This one is for more general psionic abilities, but it's far more concerned with the mechanics of psychic ability than with spirituality Shifted Perspectives
This is more about magick, and the last time I was a member it had a really varied mix of people from all sorts of traditions: Pagans, ritual magickians, chaos mages, psions, starseed and otherkin. The Enigma League - Portal