It could be an idea to add a form to gift games to people. While you can just copy and paste the key to them, the same could be said for other sites too no? The reason to be able to gift then would be more that it just looks nicer then to be given a CD key, and also it could be a way to further track orders.
I was thinking of something really simple, similar to how Humble Bundle handles gifting I guess, where it can give you a link that you give to someone, or maybe even send them an email. Both methods would have their own issues though of course.