Make the site invite only along with request an invite which will send a PM or email to all the mods on a first see first read kinda thing going.
Make them fill out a form with the requested username and info on why they want to join. I don't think a bot can beat that.
Site traffic is so low, I don't think making the site invite only would make things any better. It'd make things worse IMO.
The spamming has lessened greatly over the past week or two. Whatever Jay Jay did, worked, just not 100%. I kid you not when I say we were banning dozens a day when this first started. I only ban half a dozen or so a day now. They'll figure it out soon and move on.
Personally, I just don't understand why you guys get so upset. If anything, it should make the mods more upset than anyone else since we're the ones that have to constantly pay attention to the site and get rid of them. All you guys have to do is go right past it and ignore it. If you don't want to report it, fine, don't. I don't know about any other mods but I click New Posts every time I log onto CC to check for spam and get rid of any if there is.