For .dk domains they simply disallowed reselling domains. I think this has mostly solved this problem. I think I remember having heard cases where companies would contact domain owners with an outrageous offer and use their acceptance to 'steal' the domain from the owner.
It was passed in 2005, and in 2010 it was in effect for all domains, new and old. The article suggest there's a bigger burden of proof that a domain was registered for resale than what I suggested.
