This application lets STM or AFM images AND molecular models to be overlaid. It is useful to understand how your molecules fit to what you observed and can help interpret your data. What makes this application more useful than paint programs (powerpoint or inkscape) is the fact that the size of the images and of the molecule is fixed, so that you know that you are working in real space.
Check https://sourceforge.net/p/spm-and-mol-viewer/wiki/Home/ for updates.