best 'free' anti-splog plugin

good day,

please i am having problems ‘spam blogs’; i dont know if there exist a very good technique i can adopt to block and delete such blogs from existing on my network. i am trying to set up a clean network, but spammers are frustating my effort.

so please, help. apart from wpmu anti-splog solution that requires premium membership to access their api. is there any other better alternative.

thanks.