There's at least one OOC "phasing" guild per faction, plus a few that are faction neutral/interest specific. Most of the major ones have threads on ESO-RP: http://www.eso-rp.com/
I'm a member of The Tamrielic Forum, which is relatively small and pretty quiet, but I run into a fair share of RP out in the world so it seems to be doing its job of phasing me pretty well.
@geonsocal , there's a lot of variety in what sort of RP goes on. I know groups that live for Game of Thrones-style political intrigue, several mercenary companies and treasure hunting guilds, academies of magic that hold lectures and go on expeditions, and... there's certainly some of what @Enemy-of-Coldharbour is warning you of, but I wouldn't know about that.