> create a 1500x1500 pixel (or larger) image of pure black or white. Make it into a 2-bit GIF so it will be a small file despite its screen-filling size.
Ok, I like this answer .... but .... how about instead of a pure black or white GIF ... how about a nice looking image of the same size, but with your URL or a nifty saying written into the image, maybe saying something like, "Want a really good deal? Forget this site, and visit WW.MyCompany.com instead"
Hey, the whole idea is to bring traffic to your site isn't it? Well, why not let the offender do the work for you?