The Rock Warrior's Way: Mental Training for Climbers by Arno Ilgner
Putting aside the sort of silly title, this is really an amazing book about getting your head together to climb your best. And we all know that climbing, first and foremost, is a head-game which makes Rock Warrior's Way a must-read. One of the key insights Arno focuses on boils down to the following: stop whining about what you wish you had (ie a better hold or foot, better crimp strength, a longer reach, etc) and just start working w/what you do have. That seems like good advice in general, not just for climbing.