We have made a modification to the registration system. Instead of intercepting the registrations we have put up a simple cooking related question. If the registrant answers it correctly, the registration goes through. The purpose is simply to stop spam bots and people who don't read English. That has eliminated 99% of the spam. We'll let it go this way unless and until we get another flood of it. Note that gmail accounts are still banned. Gmail is simply loaded with spammers and the company does nothing about them.
I'm a new member, and I completely feel your pain! I admin a forum for a small non-profit, and I get literally hundreds of obvious spam sign-ups for every legitimate one. It's at the point where I'd rather have people email me before signing up so I know to look for them. The Internet can be a real cesspool at times.