If they are mirroring your content, figure out a signature of their crawler, and start serving "special" content to them.. Perhaps a bit of JS which does a wind

If they are mirroring your content, figure out a signature of their crawler, and start serving "special" content to them.. Perhaps a bit of JS which does a window.location check and redirects if it's not your own (chances are they might do some poor hostname search and replace, so you'd have to obfuscate).