Oriza-Triznyák: " This game is part of the following promo(s) [insert name of the promo(s) and their expiration date] "
I did some initial looking into this recently, as with the upcoming game pages (currently being beta-tested \o/) I finally have a good place where I could expose the info. Storage requirements would be hefty, but more annoyingly, the prices API returns a promoId when you're logged in, but not when logged out. I've made some inquiries as to what's up with that. Not certain anything will come from it, but anyway, if I can make this work, I will (eventually).
Oriza-Triznyák: - a budget tracker ( you can set the amount and add / remove games to your budget list)
I can see the use, but this is very gold-plated, and I doubt I'd make it a priority anywhere during the next two years.
Oriza-Triznyák: - export game(s) from the budget tracker directly into your Gog shopping cart
I could offer a "put into cart" link for individual products, but not for more than one at a time. I've shied away from doing this so far as my price information is running behind by definition, so I feel that sending people to the game page where they can check the actual current price is a far wiser course of action.