It would depend on how and why I left. If I were, say, leaving in protest -- something I don't picture myself doing here -- I'd want to make a statement on my way out. At other sites, though, I've just found myself participating less and less until I gradually lose touch altogether.

At least three times now, when some site where I'd been participating regularly changed format and required me to register again, I've just not bothered. I call that the site leaving me, though, not me leaving the site.