Wow... I just did a little search on google about myself and my pictures and it's quite incredible...
I have found one of my pictures (uploaded and selected here at 1x) in tens of websites of people whom I don't know at all.
Well, actually, it seems it's not tens of different websites, most are tumblr. I don't get exactly how that thing works (I'm not too much on blogs, facebook and the like) but it seems one person managed to upload the image to his blog (in fairly big resolution) and many other "re-blogged" or something...
Also found it on facebook and pinterest though.
As it always shows my name together with the image, I'm not too concerned. I even take it as "free advertisement" for myself :)
Wouldn't have thought to find this though...
I guess it's also an indicator of how popular 1x is.
Anyway, as other have said, I guess you have to accept that making an image public somewhere on the internet means taking the risk of finding it all over the place. But people should always give credit to the photographer imo.