An entirely new section, dedicated to spam only, would change the message board too much, it's just such a big step to take, letting people spam in an entire section of their own. I would suggest one thread, stickied in General Chat, and in that one thread, everyone could spam till they fall over. With a thread like that to the members' disposal, the staff could strike down harder on spam in threads other than that one. If it by any reason shouldn't work, then just delete it, or un-stick it and close it. It would be just one thread, which would make it easier to handle.

And that's just my humble suggestion, of course. =P