Since there are probably hundreds of images with no make or model identification, including non-automotive vehicles, I would suggest that a thumbnail image should appear in a specific area of every new screen within the main IMCDb site.

I belong to another forum where the idea is used merely for added interest to each page. In the case of this site, I believe it could potentially expose the right user to just one of the "buried" unknowns so that these images can finally be indexed. I know nothing about php or html, nor do I know about bandwidth concerns, etc., but I am sure that such a script can be found to put the idea into operation if more people find it acceptable.

You mean for example on the home page, or on all pages?
It could indeed be good to have an "unknown car of the day/week" (but picked amongst the old ones, as it would be too quickly identified if it has just been added)

Good idea (i've only just seen this post.!)
We did talk about something like this long ago

We did, when there were about seven pages of unknown cars ... don't remember were I wrote it, perhaps in the old forum.