So I finally got around to doing something I've been thinking about for a while. I modified my photo gallery software to add a copyright notice to the bottom of every image. The thumbnail images have just a copyright notice with the date and my name; the larger ones have the copyright, URL to the image page, and the description (if available). Now, the inlined image on the train message board shows the description, copyright, and URL to the original.
I still have a little bit of work to do. Currently all the images claim they are copyright 2004, but I'm going to add the ability to set a specific copyright date for each image or set of images. Also there are a couple of images which were not actually created by me, which shouldn't have my copyright. I'll get all this sorted out soon.
Initially I was unhappy about how the copyright notice looked on the thumbnail pages, but I reduced its size a little bit and I think it looks okay now. What do you think?