Well met.
Fellow GOG user RenKalan and I have spent some time to create gogcovers.com, a site that hosts all of your fan created unofficial GOG DVD covers for your GOG library. We are still working to populate the collection of old covers that are scattered throughout the forums, but a good portion of them are up and available now. You can also submit your own covers there by creating an account and editing the wiki.

Enjoy

Feel free to grab what I have mirrored here. It's quite out of date (no easy way to mass grab them like I did earlier) but it should be a good start.

P.S. I would appreciate a way to mass download them from your site so I can mirror them, though not sure how possible that would be. No worries either way.

This thread needs a sticky .

Awesome collection JMich. Had no idea this existed. I'll try to implement a mass download option soon.

It's mostly a mirror for the existing ones, by using a zip with the covers from last year or so.
As for the mass download, I don't really mean a "click here to download everything", but if there's a consistent naming scheme for download and name, then a script can be used to download everything and then rename them. But no biggy, worst case scenario, I manually grab the missing ones.