ability to upload multiple images and combine them to one image. Bonus if you can pick which aspects of the images to include.
one application: a cyber punk style image and a selfie. You can tell it to pull the cyber punk style and color scheme from one photo and apply to the image of the other photo. "and also, throw in the 80's looking grid in the background"
another application: you have three shots from the same shoot, same take. You like the person's smile from one, the stance from the other, and the lighting from the last. you upload them all and get the best of each.