My girlfriend and I are vegans :P And two additional friends of ours are vegan aswell.
Currently we coincide in our little bankguild together.
Ah, and I met a vegan from spain in Ascalon Catacombs once
He said, that some of his friends founded a little meet-up guild for vegans.
It’s not an active guild, though. Just a place to find other vegans, because most of them seemed to be in an active mainguild anyway.
If you find a guild or some people, let me know!