while there is some need (and certain elegance) in your anonymous system (being able to vote, use and THEN register is very good), the current system is too easy to exploit.

Just by installing some different browsers (safari, ie, firefox, opera) a user gets piles of anonymous votes!

Do not get me wrong, I fully understand that a really focused script kiddie could always create piles of accounts, no system is without failure, is just that the current anonymous system is too permissive.