Well. it is different when it is taken/stolen from the site you are on...like PP.O.
many artist aound the world have their art re-used. i actually nvr made sigs til i came here. I've done work for the web, applications, even did texture for 3d modeling in a game. lots of the things i've done probably have been re-used.
golden rule of the web as far as graphics go, if they arn't making money from it, and it's posted on the web with the artist consent . it's legal to re-use a graphic without the owners consent or knowledge.
I made a friends photography page, and he got into a small legal battle with a guy who used some of his art as a backround image. cause the site was for his personal project and he wan't making money, my friend actually gave up and said that he didn't mind if his art was used around the world. i liked his look on it and have kinda given up trying to watermark or worry a lot if i use something from someone else to make my art.
the sig's i make are from pics i find on the net, i use them to build something more personalized, with the limited space available it's not possible to credit every peice of the puzzle. so in a sence i'm stealing their work.
as none of us are making money off it.. should it be stealing?