There's a way to make hidden watermarks in photoshop, it took a bit of digging but I found a tutorial for it. http://s4.invisionfree.com/Design_Xt...p?showtopic=17
It's really nifty, and it could work if you have photoshop and you don't want to mess up the look of your photos with the watermark.
I messed with my icon just to make sure it worked (though, I didn't up the opacity enough, so it's faint even when you highlight it.) --->http://i29.photobucket.com/albums/c2...ermarkcopy.gif
, though, the trick only works in IE, not firefox. So. mildly useful, at least in point and going 'hey look, that's MY picture, not theirs'