Tom's remarks about Hough's books are terrific. I use them as my personal riding reference materials and strongly suggest to all of my LRN2RYD students that they buy "Proficient Motorcycling" and "More Proficient Motorcycling." I encourage them to read them right away and then to reread them or at least sections of them every year.
http://www.amazon.com/Proficient-Motorcycling-Ultimate-Guide-Riding/dp/1933958359/ref=sr_1_1?s=books&ie=UTF8&qid=1280797775&sr=1-1
http://www.amazon.com/More-Proficient-Motorcycling-Mastering-Ride/dp/1931993033/ref=pd_sim_b_1
Only $16.47 each and they're eligible for free shipping! That's less than what I paid for one a number of years ago at Barnes & Noble.
You could even go for three of his books on this deal.
http://www.amazon.com/Street-Strategies-Survival-Guide-Motorcyclists/dp/1889540692/ref=pd_sim_b_3
Like Tom I don't get a cut from David, although I've been fortunate enough to meet him and to hear him speak about riding. Larry