We have paintings. we have item frames. Why not have photo frames?
Photo frames would be like an item frame, a 1x1 entity on the wall, but instead of storing items, it would store memories. if you right clicked one, it would bring up your screenshots, and you would select one, and it would exit out, and the frame woud have that screenshot, surrounded by a border of leather. That is it, basically.
To craft one, you would put one piece of paper in the center, 4 leather in the corners, and 4 stick in the sides. if it doesn't have a photo currently in tis frame, it will have a picture of a random flower in minecraft. (Because why not? flowers are pretty.)
I really like this idea. Well explained and simple to use. May be difficult to implement as the photos would have to be a much higher resolution than anything else in game. I'd like to make a modification on that note:
1x1 will be absolutely tiny for a screenshot, and most monitors use a 16x9 configuration so 1x1 will squash and distort the image. I suggest changing the entity shape to something more rectangular such as 3x2 or 4x3 (the latter may be too large in game).