I asked Skuzzy about this a while back and had a conversation about it...
the logistics of it are not really doable, with what 400 some skins or something?
I agree it would be great, but how to do it? I offered to do some, but then it got into the "conformity"of it. they would all have to be the same size, and what is the best shot to use?
also the way the DL site for the skins is "automated" when it is updating, and there isn't really a way to put the image in there without doing it manually.
it would be quite a project to manually modify the skins DL page and put thumbnails in there. unfortunately it would detract from other important projects.