SWTOR Has this as a keybind and it helps a lot when trying to target a specific add in a sea of players and other effects. I usually keep mine bound to my "E" key. What it does is automatically target whichever enemy is currently in the center or closest to the center of your screen. So, instead of trying to spam the Tab key to target an add, (and hope I don't go so fast I pass it) or trying to click it manually when there are a bunch of other players in front of it, or hunt to find the correct enemy name in the list, all I have to do it rotate my camera and hit "E" and my target is selected. I think this would be a great improvement to the tab targeting system and make selecting specific targets a lot easier.