I don't really want to trade digital games I am done with but what if I have a few codes that I got from promos that I don't want but someone else might give me $5 for it? Like when I get a bundle of stuff I already own with a video card or something like that. Would be nice to go on steam and list it for $5 and when someone pays I get credited and they get the code automatically without needing to do any bargaining or chatting with anyone. Steam can handle all of that. Unredeemed steam codes should be able to be resold through this system eventually.