I noticed that the Opera browser rocketed up to 38.4% of my hits. A quick dig of the logs shows that I am being drilled by bots that look to be trying to create link spam and masquerade as Opera browsers.
I suppose eventually they will have a human help them through the captcha and succeed. I have changed things about so untrusted users will get rel=nofollow tags on all their links. Maybe that will make them lose interest and go away.
I should probably make an RSS feed for comments while I'm at is so I notice when they get through the defenses.