At least some of them, yes. But it's nice of GOG to put them together on a list and tell us about it.
I once put a list of free games together on another forum. It's in german, and divided into 3 posts (1st post is freeware, second one free-to-play and the last one fangames, special promotions, browsergames and indie devs who give their games away for free (or at least some of them)), and each one is sorted by genre; also links to sites with additional free games. Haven't updated it in a long while, but might be worth a look for all those interested:
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454