I recall seeing somewhere a request for them, so I decided to grab them (or at least those I could) and upload them. Unfortunately, trying to mass grab them failed, probably due to a naming convention (or lack of files). The images can be found here and I will try to upload any new ones I find.
The resolution is the same one that's used in the main page, which means 300x150 pixels.
In case GOG has a problem with me sharing these pictures, feel free to remove the url from the message, and tell me to take them down as well. Hope some people find this useful, and apologies if I offend anyone.

Awesome!
Thanks for your work. It's a wonderful image to identify folders in my GOG library.

Thought I'd bump this, but I don't see that much interest in these pictures.

Very nice, thanks you for your work. Many people asked for that tile images for example to add GOG games to steam.

were you thinking of this topic? www.gog.com/forum/general/gogcom_4th_annual_screenshot_scavenger_hunt

If the question is aimed at me, no, the request was actually this

Am i the only one who would like to see these tile images in their game collection instead of the shelf ?

Very nice. That must have taken a while, even if it's only about a third of the catalog. I'm curious, how were you able to save those pictures without that other junk (platofrm/price) on them? I wouldn't mind at all. These look great. Much better than those silly virtual boxes.

The images can be viewed through the source of the page (or the inspect element command of chrome/firefox) and then saved as is. They seemed to have a specific format, but trying to mass grab them like that missed quite a few. After that, I spent an hour or so reloading the main page, and grabbing the 3 images I hadn't managed to grab.
I think I've got them all, if anyone sees any other picture, just tell me which game it was, and I'll try to grab it.

Ah, okay. I just managed to load a few myself by swapping out the games' name in the address. It looks like only a part of the catalog got that treatment as some other games which weren't on your list I tried netted me a GOG 404 page.