Nice blog outlining one woman’s crusade against all types of spam. It’s actually a nice resource for anyone wishing to track referrer spam, bots and more:
I’m thinking she has a fairly hefty referrer block list.
My referrer blocking attempts are semi-successful so far. I found I had to block by IP number rather than by domain name for a few. Not sure why, but that seems to have done the trick for the more stubborn ones.