Personally, I only put a copyright on the ones on my website. I've had a person once steal a picture(a good picture) of Sassy and post it on a website that said they took it, so after that I copyrighted all my GOOD pictures. If you want to take a look, you can see them on my website(in my siggy!). As Michelle said, if I use a watermark, and it's better across the center since they can't just crop it out of the corner.