Icons by page, like link images

I’d like to associate an icon with a page (or, I suppose, a post). I can do that with an element from the blogroll just by assigning an image to it. Can I do that with a custom field for a regular page?

Or, even better, can I dynamically have the theme look for an icon with the appropriate name? I already have the theme assigning a stylesheet based on the current page’s name and another one based on a set custom field. I don’t know how to get the metadata for the target of a link in the page list, though.

Hm. I hope that was clear. If you think you might be able to help, but can’t quite understand what I’m asking, please ask me and I’ll clarify.