Mentor Mode
It's really hard to get help or to help people because the spectator has a time delay, there is still no replay functionality, and it requires the use of an external chat program, which not everyone can use without inducing excess lag. What would be nice would be to have a special spectator mode called Mentor Mode. In mentor mode, the watcher gets 0 information the player does not have. He sees EXACTLY what the player does, no added camera controls or other functions, but he sees it in real time. Essentially it is streaming, but only to 1 person. In this mode the mentor could type (only visible to the mentee) in game chat. The advantage of having this built in is that streaming is taxing on the streamer's system and makes the game act differently and there is no way in-game for the mentor to chat. This could be handled by RIOT's servers just like spectator with no impact.
This mode would only be available in normals since in ranked it could be used to have a second person spot incoming ganks (although you can technically just use streaming to have that happen right now anyway).