The most interesting warning I've ever seen in the source code of a blog was at mybluehouse.com. It reads:

"If you're just peeking, peek away. But if you're planning on taking my weblog layout and/or images I assure you that I'll come across your site eventually and when I do, I'll make you feel the sharp pain of my foot kicking you in the behind. Then I'll make your life real hell for a while through a variety of ways. Promise."