Spiritual Combat Revisited, by Jonathan Robinson/Lorenzo Scupoli. Okay, I'm not so much reading it as putting off reading it. It's a good book, but it's hard for me to go more than half an hour or so without succumbing to a rather dry stretch and dozing off, which I think speaks more to my reading habits than to the writing. Almost every time I pick it up, I find some nugget of wisdom, but I just haven't been able to maintain enough momentum to plow through the whole thing and reap the benefits of taking the book as a whole (or at least larger chunks) instead of piecemeal.
You can find a review of it here.