Links to articles on the game's pages in the catalog
More payment options (I'd like to use my debit card instead of my credit card)

How about video reviews?

I just tried look through what kind of games are on wishlist, so I could either give my vote for them or add games missing and I would like to see.
But as that forum topic is thirty pages long, each page has twenty or so posts, it is huge amount of stuff to read through! And this is just third day, what it is after few weeks? :)
So, there has to be some system, similar to catalog now for games, where you can search&browse titles already wished. If title is already there, you could mark +1 for it, and no need to duplicate it on forums then :)
Those games could have some fact sheet too, showing release date, releaser, game type etc so people can find good old games from there too, if not yet downloadable :)

It would be easier to just have the ability to set poll threads and then people could vote rather than leave posts.
I also don't see the point of the rep system if no one is going to use it.

-> RSS for news.

See my thread on You Tube links in the meanwhile....! (General Discussions)

Email list for new games when they are released on GOG

I believe there is a box you tick for a newsletter that is coming soon it says.

I just want one thing! Trailers ^^ gameplay ofcourse. That would make a uncertainty a clarity

Not an official thing, of course, but poster UK_John already started a topic for YouTube videos that could act as trailers for each game currently available.
You Tube Links to all the games currently availablefrom G.O.G.

http://www.gog.com/en/frontpage/rss

Thanks
/me goes to eye doctor

I would love to see the ability to run all games in windowed mode and/or at widescreen aspect ratios....playing games that are stretched out is not my idea of fun.
Additionally, it'd be great if GOG included some or all of the freeware patches floating around that allow older games to be run in hi-res such as the Highresolution patch for Fallout. That's currently my biggest gripe with the service...the inability for some games to run windowed in high/widescreen resolutions.

An invite system for the beta. I know a lot of people that want to join GOG beta but haven't received the email yet. Will be very good if I can invite them.