I have read a number of motorcycle publications and there are three books I can highly recommend.
Firstly the book that needs no introduction, the famous Twist of the Wrist (vol 2) from Keith Code. A performance riding handbook that explains in everyday terms what is happening when you brake, corner and accelerate on a motorcycle which has helped many people. A easy to read book that you can revisit many times and which improved my riding dramatically. The focus is mostly on going faster and my thoughts recently have shifted from performance riding to improving my safety margins so this book is something I think would best be enjoyed by newer riders or anyone doing track days or keen to take their riding up a level.
My most recent purchase has been Proficient Motorcycle Riding (vol 2) by David Hough. The author has been writing for American motorcycle magazines for so long that he now is retiring and has gone back and put together all the best information and articles and stories about every aspect of motorcycles and road riding skills and how to stay safe. The book has a huge scope from motorcycle behavior to advanced riding skills and many safety aspects quite simply it is the best book about real world motorcycling I have ever come across.
Lastly I want to recommend a book that is a great motivator to get out and ride. Regardless of what you may think of the movie stars Ewan McGregor and Charley Boorman they did get out and do what so many only dream about and their tv show was some rare positive press for motorcyclists as well as the spark for numerous people to try their own adventure. The book is significantly better than the tv series and a terrific read. I really was disappointed by their second series through africa however purchased that book recently in hope that it may be better as was the case first time round. Will let you know, until then this book rates very highly with me given I like real life travel stories, add motorcycling and alot of humor and private thoughts cut from the tv show makes for a great read.
Update: well the book of their second tour is same as their tv series in Africa - not so good.