Fiction about a book

[SilkStalkings]

Just reading Mr Toppit by Charles Elton and thinking there must be a whole load of books where a book, made up or real, is like a character in it's own right (or maybe just a McGuffin, to use a film studies term.)
Where a book has a profound effect on various characters in different ways and the reader perhaps solves its mysteries and everyone gets closure terein. Examples off the top of my head:

I Capture the Castle by Dodie Smith
Book of Dave by Will Self (no closure there though you bastard Self!)
Any more? There must be lots.

I read Mr T on holiday a few years ago, when reduced to scrabbling around for books in the apartments. I remember v little about it but quite enjoyed it.

Books within books:

The Book Thief
Inkheart by Cornelia Funke - this is a children's book but v good
The Historian
There must be loads more, but these are the first three I can think of.

Mr Pip

Clive Barker - Mr B Gone

The Little Book by Selden Edwards
Shadow of the Wind / Angel's Game by Carlos Ruiz Zafon

The Saddlebag by Bahiyyih Nakhjavani. An awesome book (in the true sense of the word) and no one I speak to has ever heard of it, let alone read it. I always highly recommend it.

The Eyre Affair - Jasper Fforde. Several books, characters from books and poems appear and are central to the plot.

Diamond Age - Neal Stephenson
Sweet Tooth - Ian McEwan

Atonement

The post modern ending was devastating

Cloud Atlas by David Mitchell is also a series of books/manuscripts within books that the characters are reading

Oops xposted with Back2Two

My life as a fake by Peter Carey, about someone who wrote a book as someone else and it all went wrong. Does that count?

One Damn Big Puzzler - John Harding

The Neverending Story! Classic!

Hurray! I now have a holiday list!
Dh's contribution: 1Q84 by Murakami, Kurt Vonnegut