My blog is fairly impervious to comment spam. I've got one or two comments that I had to delete, but I can respond fairly quickly because I get a Jabber notification of comments. I think the ajax comment mechanism does most of the filtering.

I just discovered that I am not impervious to trackback spam. Turns out there was a lot that I didn't even know existed. Luckily, I didn't have a single valid trackback so I could just do this at the rails console:

Trackback.find(:all).map {|t| t.destroy}
Article.find(:all).map {|a| a.allow_pings=false; a.save}

I also changed the default allow trackbacks setting to no. Trackbacks are a neat idea but obviously not one that works.