I put together a little project that attempts to gather the "zeitgeist" image from a particular web site, and returns it.
Here's how it might work... Imagine a message boards application, like PHPBB, for example. As you type in a URL to share, a little bit of javascript gets executed which loads an image from a remote page for you to include with the link.
Here's a Web 1.0 way of illustrating it (I need to get a nice AJAX library installed on my blog, so the 2.0 version is forthcoming). Just type in a URL into the box and click "Go". A new window will open with the "zeitgeist image", if there is an image that seems suitable. Works on sites like flickr, but not so much on google, although I suspect I could tweak it to work.