I was just thinking about all of the unsolved threads, the ones that actually are solved, and I was thinking, maybe @Dani could add a 'Please Mark as Solved' button that users could click to notify the owner of the thread that they should mark it as solved.
Obviously, this could be abused, but if we put specific limitations on it, lets say, only let the user click it once, or limit its use to Moderators only, then maybe we could all help clean up the "unsolved" threads.
Just an idea.