The output from the sonarviewer saved as a PNG-file is great to highlight an object found underwater since it includes both sonar echo amplitude, downscan, and sidescan. However, it is a bit annoying to just have the GPS coordinates at the top as a reference for where that object is.

It would be nice to be able to save a sonar viewer image as a point-of-interest. After going through an area, I would like to be able to export all points-of-interests as PNG files along with an ESRI shapefile with the positions. Then I could just pull the shapefile onto a map in QGIS to display where each figure comes from. Perhaps let me name the points too, instead of giving the coordinates from the GPS.

Waypoints should give you pretty much all of this functionality right now. You can create a new waypoint in the sonar viewer window by using the "drop pin" mouse mode. Although waypoints won't actually show up in the sonar view, they will be shown on the map view. Waypoints can be named, and waypoint sets can be exported in the ESRI Shapefile format as points, with the names held as an attribute.