I was considering a mod where you could launch a replay (with multiple people), zoom through to some point, then stop the replay and take control of the armies in the game. Might make for interesting "what if" scenarios for close games, or a training tool for players who just need to find their feet after an initial build.
I am interested in how the engine treats replays differently from live users, specifically if a mod could be made to parse the replay and forward those commands to the game until the users decide to take control.
dstojkov also suggested looking at the multiplayer game save feature, you could zoom through a replay to where you want, then save it and launch again with friends.
Maybe other people have thoughts on how feasible either of these approaches are?