I use CCD Inspector. I was a betra tester of the orginal. Its good for autosorting a large number of LRGB frames in order of sharpness using FWHM of stars in the image. It has some nice feratures to analyse the proifile of your optics which can tell you how your collimation is, if your camera is tltted etc.... If you have lots of money and want to tweak the absolute best from your setup them its worth it, but otherwise you can live without it.