It would be a really cool feature, if there would be a friend-only ranking at graveyarded maps, where you can see how your friends played this map. Like at Cheatreal. If you have high-ranked friends in your friendlist you could mess with their scores, and you could battle with them for fun. Also you could compare with their scores. It would be much better, then sending screenshots/replays all the time, but I don't know how much work would be behind this.