I agree that watermarks can ruin a photo, and are usually annoying if used by amateurs.
If you really want to protect your work, use a digital watermark, like Digimarc (which is built into Photoshop). And register your copyright. That gives you definitive proof that something is yours if you need to take someone to court.
http://www.cipo.ic.gc.ca/eic/site/ci...h_wr00003.html