There used to be /l/ - Lolicon back like 12 years ago. Also /z/ which was nothing but a picture of a guy's dick covered in bees. Also /fk/ - For Kids, a joke board moot made. /z/ and /fk/ you could only access if you went directly to the board by typing the URL but it seems they've been removed now. /pol/ used to be /new/ before /new/ was removed and came back as /pol/. It wasn't nearly as cancerous as it is now.