I haven't read all the suggestions so far, but I've seen one that I'd very much like to see myself.
The option to purchase games without using creditcards or paypall(for which one is required in Belgium, which makes it utterly pointless). And I'm not getting a credit card either, the only occasion where I need one is to make online purchases, I can easily use my maestro debit-card pretty much everywhere I've been in Europe, and that one is free(or at the least included at my bank), while I'd have to pay just to have a credit card, which will then charge intrest every time I use it...
So could you pretty please allow bank transfers to purchase games? It's much, much easier for us young Europeans.
This site looks very promising though, I haven't found the titles I was looking for but I'm sure that'll improve over time. Now if only you give me the opportunity to spend some money here. :)
As an other idea it would be nice if you get all the contents you would have gotten if you had bought the game. For example if you had bought Baldur's Gate you got this nice map and book of spells etc.
Although I don't really expect you guys to improve how well games work with wine, mentioning how well they do, would be a handy feature.