Anything free service is inevitably abused, so you charge a nominal amount. Even if it's just £1 it would stop evil people releasing thousands of spam flavoured titles each.
However, the real solution would be to simply identify duplicate works. If someone tries to publish something that's over 90% the same as a previous work, then there's surely something to investigate...
_________________jonbwfc's law: "In any forum thread someone will, no matter what the subject, mention Firefly."
When you're feeling too silly for x404,
youRwired.net