You could use this as an in-game screen-shot feature (instead of having to printscreen, paste in paint, etc), or my personal use, use it to take snapshots of the current game screen for save menus. With the module update, the processing takes a lot less time if you specify the size you want, instead of relying on the clear_rect() function. Can also be used as an in-game camera, if you wanted a mini-game like that.
The forum doesn't like Kanji, so please see the link to the original script Jaffer provides in his topic for proper accreditation