Render History script
Created by Victor Barberan, he writes:
I made a little script for keeping a number of renders inside the image editor, as a form of 'Render History'. I think this is very handy to compare the changes in your render.
This way every time you made a render the script automatically saves the image, load it in the image editor window, assign a name to it, pack it inside your blender file, and then remove it from the drive.
You can have your render history inside blender without doing anything, even if you save your file and open it later you will have your render history.
There is a variable in the script called 'NumRender', you can modify its value to set the number of images you want in your render history.
AutoSave Render script
Created by macouno, he writes:
This script will automatically save every render you do as a separate version. I wrote the script because I do a lot of test renders when working on a project. With this script every test render is automatically saved, which makes for a nice progress storyboard.