YouTube Subscriber Notification
We all know that you can connect your twitch to your youtube account. By doing that, viewers that are watching your videos right now while you're live at the same time on twitch, receive a notification that you're live on twitch. I think it would be cool, if subscribers who subscribed to your youtube channel, received a notification when you're live on twitch. This is of course only possible if youtube would agree on this idea, but I hope that's going to be an option in the future.