suncalc.org — Computation path of the sun
Camera Depth of Field Simulator
ansel is an open-source photo-editing software for digital artists, designed to help you achieve your own interpretation of raw digital photographs.
Flip plugin lets you seamlessly transition between two states even if there are sweeping changes to the structure of the DOM that would normally cause elements to jump.
Focus plugin for lightroom shows you which focus points were selected by your camera when the photo was taken
Understanding Darktable — youtube playlist by Bruce Williams