I'll admit, I'm no expert, but one member mentioned requesting royalty payment, and I agree with them. If someone steals my content, maybe first you could try to further monetize the situation. See if you can get a profit from it. Contact the site owner and make an offer; they keep your content, but they have to pay you $x/month, or x%/month.
It's worth a shot, and at least you could get some $$$ from it.
It's worth a shot, and at least you could get some $$$ from it.