Here's an idea:
A book almost like a log where you can put screenshots in and take notes maybe with a to-do list or a grid for building plans on separate pages.
Whenever you take a sreenshot, it could ask you if you want to keep it in your notebook or not. I think it would make it a lot easier then going to your bin and dragging out the saved screenshots just to have a quick look at them. For the grid, it could just be a simple 32x32 grid just for floor plans or profile plans, nothing too complex. For the to-do list you can add things to do and check them off when you've done them, almost like personal achievements. For notes you could just type whatever you feel like on a page, whether it's coordinates of an area or just something like a journal that you write something in every day. Another possibility: a crafting log that keeps crafting recipes only for items you have obtained or crafted before. I also think this notebook will come very handy in multiplayer, allowing you to show building plans, show screenshots, show your achievements, share crafting recipes, and share notes with one another. The user interface will pretty much be just like the map, except your cursor will be able to be moved freely to open other pages of the notebook, type notes, use the grid, etc.
Crafting Recipe: I'm not sure of the crafting recipe yet, feel free to post your recipe idea below
Maybe if this gets enough support, i might make a mod for it
I wouldn't want screenshots interfering with my gameplay. I took a screenshot, I forget about it. Then I close the game and look at it. I'd be all for it if it were just keeping notes and schematics.
What I was meaning was it would be more useful in multiplayer, allowing other users to see screenshots either from your single player map or another area of the multiplayer map, instead of having to get it out of the .Minecraft file and send it to them