Well, Ollie started it, so how about everyone posting the cover of a book they think is worth reading (go to Google Images and search for the title, then link to it here)?

A few for starters:

     
   

Four Eggs In One Basket:

Sorry, how to post images? I don't know.

It is a fantastic work, yes. This is what you were looking for:

   

Oh yes, his books are very well-known and generally seem to be much enjoyed and highly regarded. 'Piano Notes' is the most recent, I think, amongst the others most worth reading are The Classical Style, Sonata Forms, The Romantic Generation, Critical Entertainments, Beethoven Piano Sonatas: A Short Companion, Schoenberg, and Romantic Poets, Critics and Other Madmen (not about music in the latter case, basically a collection of NYRB reviews, but very worth reading). Can't resist giving some more covers (just love the fact that pics are possible on this MB):

                           
            

I recall hearing that mentioned somewhere (wasn't from me, though) as well. I'm not sure if that would be as good as his earlier books, as almost none of his other writings demonstrate much knowledge of or interest in, any modern composers other than Boulez and Carter (about both of whom he is very eloquent, though). He dismisses Stockhausen with a single sentence somewhere, and I'd be very surprised if he was really one to deal adequately with the influence of American experimentalism in America, Europe and elsewhere. Nonetheless, I'd still like to see that book - somehow it reminds me of the long-promised but as yet unmaterialised third book on Gunter Schuller's jazz trilogy (following on from Early Jazz and The Swing Era, there is meant to be a book on post-1945 jazz; his book Musings: The Musical Worlds of Gunther Schuller contains some interesting stuff in this respect, but is not remotely comprehensive like the earlier books were).

Also, a book on the second half of the 19th century from Rosen (to follow on from The Romantic Generation) would also be very welcome. There are three really excellent essays on Brahms in Critical Entertainments, however.

Even so, a big meaty book by Rosen just on Boulez and Carter would do me very nicely for starters .  

One other book I would like to add/second a recommendation for is 'The Singing Neanderthals' by Steven Mithen. I read this as a result of Veronika Lenz's advocacy in Another Place but since the poor girl is gagged and muffled in a sock drawer just at present (in humane conditions I am assured) perhaps I could mention it on her behalf.

Steven Mithen is, well, a bit of a renaissance man, but his day job is as a paleo-anthropologist and the book is essentially a look at the early development of music (how and why) from the point of view of evolutionary theory and pre-historical study. It rescues music from its previous role as a small footnote in previous such studies which, for perhaps obvious reasons, tended to focus on language. A lot of it is naturally pretty speculative stuff, but that is in the nature of the subject and Mithen is the first to acknowledge this. But it's a great read and absolutely packed with fascinating and thought-provoking material relevant to music brought together from varous disciplines, for the first time it would seem, in one place.

He got me on side straight away by admitting at the outset that, although music meant a great deal to him in his life, he was the only member of his family who could neither play an instrument nor sing in tune. The book was partly his way of 'joining in' with an activity he regarded highly. I had great fellow-feeling with that one  

Playing with the thumb under in scales is one of the biggest mistakes in much piano teaching. Do you know György Sándor's On Piano Playing (to my mind the greatest of all books on piano technique, and that which made me want to study with him)? He has a lot to say on that subject.

Rosen's stuff about the 'beautiful tone' school of piano playing (meaning - always top-voiced, without any discontinuities, with continuous use of the pedal, always changing with the harmony) in that book is also very interesting.

George - how about a cover for 'The Singing Neanderthals'?