I've never really considered watermarking. I find it ugly and, well...you can't use an image off the net for print anyway. I always drop my images down to 72dpi as that is the most a screen can register, anything more and you're just taking up space and time. You all know what a print out looks like from the internet. So no, I don't watermark. Besides, if somebody did use my image illegally, I could probably get more money for it retroactively than if they had asked to purchase it legally from the beginning.
