Marc - FYI...

Marc - I came across a site where quite a few of your photos were posted. You may not care and may even feel it is good advertising. The owner of the site did give you attribution, although you may want to talk to them about getting your name spelled correctly (Adams instead of Adamus).

I gotta run but I thought you might like to know. BTW, others here might have their photos posted there too...

http://debsy.stumbleupon.com/archive/50/

Oh, yeah, those guys again. No surprise there. They've been doing that to me for years and have a tendency to ignore notices regarding copyright infringments.

Ok - at least you are already informed. It was a surprise to me when I saw them in my referer logs so I checked the site out.

Marc, go to the source of the problem.

Stumbledupon.com is hosted by Layer 42 (layer42.net), based on the DNS registration for stumbledupon.com in their whois record. A nicely worded email to abuse@layer42.net may get you some joy. Point out that as the internet service provider for this site, you view them as jointly liable for the copyright infringement being carried out by their client.

IANAL etc etc, but I have seen this approach (ie go to the physical ISP hosting the site rather than the site administrator itself) work before in similar circumstances.

Most hosting companies take copyright infringement very seriously. They most likely will take action if you contact them

The way I worked around this sort of thing is I put a small copyright notice on the image itself, so it basically serves as free advertising, like Geoff mentioned. You could do something like "© Marc Adamus (www.timecatcher.com)", neatly tucked in the corner of the image, but noticable that people will know where to go to see more.