I was not aware that bjj.org had a page with many school logos. Many of these are pretty cool. Check it out: http://www.bjj.org/logo-gallery.html :icon_surp
Those are cool. IMO it's pretty hard to beat something simple and direct like this: Some of the "tough guy" ones are a little obnoxious.
Though I don't train with him, Michael Jens's logo struck me as pretty nice. http://www.bjj.org/a/people/jen-michael.html
triangles are a pretty popular symbol - looks like nearly half the academies use some sort of one. i gotta dig up that thread on why their used.