Why We Love Middle Earth
Just the right side of annoying (and forgivable if you have listened to the Prancing Pony Podcasts) this book is an absolute Moria’s worth mine of information on all things Middle-Earth related. It is interesting in its subject matter, inspirational in its coverage and yes, I do want there to be a second volume guys!
This is probably the best introduction to the wider world of Tolkien (beyond the books themselves) as it covers what to read next, Tolkien in other media, Tolkien studies and the books place in the wider world of literature. Obviously none of this is covered in any great depth, and each subject is discussed in more detail in more specific works but for a general overview and a kick up the backside to start studying the rest of the Tolkien universe this cannot be beaten!
If I ever take an extended break from Tolkien for a while this would be an excellent re-read to get my head back in the game.