I looked around but couldn't find any ingame Notebook to jot down some ideas or keep a list of stuff.
So I thought I'd suggest it here for folks to make it(technical as I am, I am no programmer

)
Out of the top of my head, some features that would be neat:
- Multiple pages (instead of one big page, making it messy with a lot of text)
- Organized, perhaps different 'books'
- Text editing with basic functionality
- 'Sharing' books with others having the same mod(maybe even as crude as able to send the raw textfile via email to each other)