Most posts contains both text and photos. This content could be great in a photoalbum/book (or even as a magazine). It could be a storytelling book (pictures with a lot of text), or contain only photos.
Content should be easy to choose by clicking on the post or choosing to print/order the content of a category, tag, month and so on.
Example: I make a blog for my children, for them to read while they grow up and as a memory when they are grown ups.
Every year I would like to order a physical photobook, by choosing the category for each of the children. Or a photobook containing all birthdays from the last 10 years. I hope you catch my drift :)
When blog-content is chosen it should be possible to edit each post, f ex by removing text or picture. Further on there should be functions like adding background, heading and so on. I don't know wether this should be done in wordpress or after it is exported to a photoprinter (or what it is called..). Or maybe a pdf could be made? Then it would even be possible to print it out yourself (with a homemade soft- or hardback cover)
It should not be possible to add posts containing videos, as videos cant be printed :)
I hope you see the potential in this idea, imagine all the photobooks and blogmagazines waiting to be read offline :)