I've come across some tools for ArcGIS that would also be great additions to Global Mapper. These tools synchronize your map extents in Google Earth (in Internet Explorer, plug-in required) with your view in ArcMap. So the suggestion is to have a tool in Global Mapper that will synchronize a Google Earth view based on the Global Mapper map extents. This functionality would be great for Global Mapper given the constraints of how much online imagery you can pull into the application on a daily basis (if all you're doing is using the imagery for reference). There is a YouTube demo here:
YouTube - Integrating ESRI ArcMap with Google Earth API
Along the same lines, it would be very handy to synchronize instances of Global Mapper as well. So you could have 4 Global Mapper sessions tiled on your screen, with all map extents linked - could allow you to view multiple layers of data all at once. This is very handy. I hope you will consider this for future development options (or even better, is it already being developed??).
Thanks,
Steve