The people out there with some of the best insights into your game are the fans. They have played the game and they know what worked and did not. Their feedback is always worth heeding. Press tours, demo'ing the game at tradeshows and evangelizing your game are all positive steps in getting your product not only out to the public, but if done right, getting everyone as excited about the game as you are. All is not as exciting as some of the tasks mentioned above, however.
Scheduling is probably one of the most important tasks done on a project.
Not only setting up the initial milestones, budgets etc. Making sure your people on the team are able to do their job should always be a major concern, as well. It sounds silly, but making sure your artist has a good computer, your modeler has adequate concepts, your designers have the right book resources etc. is sometimes overlooked as a very important task for managers. Your people ARE the project, you need take care of them. This is just a very small sample of what goes on alongside the traditional concept of making the game.