vBulletin had this -amazing- addon that checked for a load of things, and if someone posted spam words (which you could set) or stuff like links and images (all configurable) on their first x posts (whatever you set it to) it would put the post(s) automatically in moderation queue (or other actions, if you preferred, I think) and no spam would reach the board itself. Very occasionally caused a bit of a problem if someone just joined and tried to post something with a link in it, but other than that it stopped all spam except for 1 single post that managed to came through.
I kinda miss it, but Jaxels addon + some questions are quite capable to stop most spam for me as well, so far.