I'm pretty sure that demos would, at the very least, delay the release of the games. And you wouldn't want a demo that would not work on your operating system, when the game does. That would be actually hurting the perception of the game, the opposite of what a demo is supposed to do.
I think that 5 bucks (or 4-something euros) is cheap enough that you can take the leap of faith if you are not sure, and not feel bad about yourself. It's about the same as a lunch, and you don't ask for a taster before a 5 dollar lunch.
That said, most games in GOG are amply documented on the internet, and while reading about it is never the same as trying, it should reduce disappointments to a minimum.

I love the fact you guys post the mods that work with the games in the forums. Could you put them as stickes so they are always at the top of the page?

+1 for paypal
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+ i would like to see bundles of games, like all games from interplay for special price, etc

I would like to see "Discuss this game (with community)" button or link on site of each game and this button/link will redirect you to relevant part of Community Discussions.

I would love to see the metacritic game score in each games profile. you know, steam style.

I'd like to see (if possible) an online backup for savegames. It can be really useful when your system dies and you need to reinstall it. Whole game can be re-downloaded, so online backup would be a nice additional feature.

intresting idea but obsolete one I think. first of all each game stores savegames in diffrent file format and disc location so making an application to automatically upload and backup can prove rather difficult and/or human resource consuming as it would require profile to be written for each game.
secondly, right now you can manually store files to the cloud (ie. Microsoft Skydrive or even Gmail) so making your own internet repository of savegames is only a few clicks away, even without fancy applications from GOG :)

i see the "game requests" thread managed to get more than 5 pages in a single day. maybe it would be better to create whole forum "requests" and then, a each game would represent the topic, then everybody can add his own opinion on the matter and admins react or reply, whether is it possible or not. that way it would be way more manageable and easy to navigate in not only for users but also for the ones who moderate it
if you're not sure what i mean, check requests forum at abandonia.com
edit: also, it'd be nice to see who posted last in a specific topic when viewing forums

On the other hand, I see no reason not to link demos that already work. I'm not sure about Vista but it's apparent that some of the games in today's catalogue have XP-compatible demos (nowhere to be found at GOG.com).
But I agree that porting the demos sounds unnecessary (after all, I can use another computer or an emulator, if it's just for a try).
I see your point, demos have saved me a lot of money by _not working_, but I guess GOG is another case, as they guarantee the OS compatibility, and are gaining my trust regardless of (absence of) demos.For some people, it's more like 5 lunches. You should never underestimate the value of (your customer's) money.Yes, I can read about them, and yes, I can find the demo, and in fact, I will. But why shouldn't I have it the simple way?
(I don't trust professional reviews so I don't need them (or metascore) linked to the games. Demos are fine though.)In fact, creating the "profiles" would only require a few hours per game, which is not much compared to the time it would take to create the client and setup the server or the time it probably takes to prepare each of the games for the shop.

now i wanted to buy a game but there is credit option only:(
i don't own a credit card (only payment card, that cannot be used to purchase online stuff) and i'm definitely not going to get one in near future
why not letting your members paying via bank account transfer? each member could have his own bank deposit code, i can't see any problems with this option

-Gifts to other user accounts, or to non-users via e-mail
It's been mentioned in other threads, but:
-Windowed mode wherever possible (has the team tried a software solution like that Direct 3D windower that floats around the internet?)
-Links to Mod and community patch sites where relevant (either on the game page itself or on the relevant sub-forum). For example, the Hi-Res effects and textures for Freespace.
Also, while I am generally against download clients, something that integrated a download client with the software needed to emulate DOS and/or force games to run in windowed mode (or added other such features) would get me to change my mind.

That's the program I was talking about. The biggest problem with it is that it doesn't always work (For example, I couldn't get it to window Command and Conquer: Red Alert while trying out the copy EA put up for free to promo RA3). The basics are that the > and x buttons start and stop the "capture" or api hook or whatever process actually grabs all the screen information from the game exe and displays it in a window, and the + and - buttons add or remove .exes from the list, and the folder button to the right of the + and - give you a bunch of options (mostly in english) that I've generally left alone aside from window dimensions.
In any case, the fact that this program exists says to me that it should be at least -theoretically- possible to either force or fake a windowed mode using Direct3D/DirectX in windows. Of course, I Am Not A Programmer, so I could be talking out of...well, someplace other than my mouth.

An OPTIONAL "gog's games download manager" appears to be the best way for everyone =)
I do not feel comfortable having to download and check all games one-by-one, and some people do not feel comfortable with a computer application installed listing all games in account and helping this download, if we can join the best 2 worlds with an optional aplication, it's perfect!

What about a GOG PUBLIC profile page, not sure if there already is one, but if there isn't it could have a link like http://www.gog.com/profile/sirbaron
Do not confuse this with the my account section ¬¬
You could have a blog section so you could write a blog if you so wish, it shows a list on a sidebar of the games you own, and another table can show all the reviews you have submitted for each game you purchased, along with the rating you gave it.

My Wish: To have a wish list :-p It would be nice to add games to a wish list if you want to buy them but don't have the money now, and want a bunch like I do.