It seems that there are as many definitions of producer as there are projects. Certainly many project types define the role differently and have different expectations depending on whether the producer is working in broadcast news, feature film, or corporate communications.
What they all have in common are:
• management of the project from beginning to end;
• budget and deadline accountability;
• expertise in technical, creative, and/or content requirements of the program
Some projects I have produced:
30-second commercial for New York City office building, broadcast on the Golf Channel and multiple TV stations.
Training video for Morgan Stanley financial advisers
Documentary-style fundraising video for the Episcopal Church's national headquarters. (Emmy nominated.)