If you'd like to know how to watermark digital photos, check out About.com's guide. Author Michael Carr concludes it's probably the most effective way to protect images from online theft. He discusses watermarking software, creating your watermark, and then finally how to watermark your images.
If you'd like to see an example of watermarking, check out some of the images on digital camera sites that steal product photos from dpreview or Let's Go Digital. :)
