Sorry if this is obvious and I missed it, but is there a page that just lists the current games that are on sale?

Not really referring to whatever current news page tells me that X Company's Games are all on sale, as that still requires me to specifically hunt down the news.

No such sales page I'm aware of.

Edit: I guess GOG could add a new option "on sale" to the price filter in the games catalogue...

When you go to games catalogue, then games on sale have their price on orange background. Look there at Star Wolves to get the idea.

There's no such page, but you can always find a direct link to the current sale (if any) on the main page. One of the five smaller banners in the middle always takes you to a list of all the games that are on sale. That's almost as good as a permanent sales page (requires just one extra click).