If you don't have too many new registrations you can vett people by allowing them to provide proof that they are real by:
Giving a real name
Giving the name of their facebook page or blog
Articles they've written
etc. If they're interested.
It doesn't always work for people to do that though. I have a couple of fans of my blog that remain anonymous because they don't want to be searched, which might lead to trouble getting jobs or keeping the one they have because they're considered to be psychic fruit loops.