Many of us have proposed increased service. Some of these include increased service on existing routes while others include new routes. I want to keep this thread to new routes (either including at least one new city or new route between two existing cities) as opposed to increased service on existing routes (although a reroute of an existing route can be included).
Some I remember being discussed by people other than myself...
Gulf Coast, New Orleans to Jacksonville (since currently not being used, it counts)
Toledo to Detroit/Dearborn
Dallas/Ft. Worth to Meridian/Atlanta
Reroute of Southwest Chief to include Pueblo
Oklahoma City to Newton, KS
Feel free to suggest others, especially anything that includes the largest major markets that don't presently have Amtrak train service.