Spam is an annoying but not threatening problem. I usually manage to remove it within a few hours, so the best way of avoiding it is to subscribe to the daily email update rather than getting an email every time someone posts, so there is a good chance the spam will have been removed by the time you get the update.
I have also been through the list of registered users, banning the obviously machine-generated names. There is a risk that I might have banned legitimate users, so if you suddenly find yourself unable to post please drop me a message and I will reinstate you.