I like SSGD (Sex, Sexuality, and Gender Diversity), although I don't remember where I first saw it.
I don't really have an opinion, as someone who's not intersex, on whether or not the "I" should be added. Obviously I don't think intersex people should be left out of the fight for human and civil rights, and those who want to be activists should obviously be included. But since they've not historically been a part of queer communities and cultures, I don't necessarily know that tacking them on to the end of the acronym is meaningful; the push for that would have to come from intersex people wanting to be included, not from LGBT people trying to be inclusive.