I haven't really looked around what other people's ideas (or implementations) are on referrer spam, but I think these idiots who want to use our blogs as a way to boost their Google rank are setting themselves up for trouble, because we are not really stupid. For the time being, I am simply letting it all run to collect evidence. There are wonderful things we can do with all these spam URLs. Distributed denial of service attacks come to mind ;-) Or just redirect them to themselves.
Seriously, I am thinking of having word filtering and a manual negative list in the blog engine and to expose that list as a separate RSS as well as to allow import of such RSS lists into my blog engine. My exported list might also reference all my trusted negative lists that I import, so that this forms a mesh where folks can report those idiots and the engines will pick it up and throw out the crap.