Some things that would make a great program even better!

1) Lat/long grid in particular for the Data Viewer (but nice for the "Data Selector" also). This would be a great aid in location and tracing paper overlay/ploting activities

2) Dataviewer Annotation: The ability to mark points on the screen (like you can with Google Earth) - this would be the current position and estimated positions etc. And a measuring ruler thing (like Google Earth). Currently this is done with tracing paper stuck on the screen and is a real pain!

Keep up the work- stunning product!

Cheers