Books I'm really glad I read when I was starting to learn the game: Winning Ugly by Brad Gilbert and Steve Jamison, The Inner Game of Tennis by W. Timothy Gallwey, Smart Tennis: How to Play and Win the Mental Game by John F. Murray, Tennis for Life by Peter Burwash, and The Art of Doubles by Pat Blaskower.

Tennis biography I enjoyed the most: Open by Andre Agassi

Other good bios: Breaking Back by James Blake and Days of Grace by Arthur Ashe

My fitness Bible: Complete Conditioning for Tennis by Kovacs, Roetert et al. These are the fitness gurus at the USTA national training center in Lake Nona, FL.

Must haves: Friend of Court (PDF) published by USTA, includes the ITA rules of tennis, USTA regulations, and "The Code" regarding sportsmanship. You can also get a hard copy from USTA.

For history and cultural influences: The Bud Collins History of Tennis by Bud Collins

While we're at it I will mention that there are absolutely no good tennis movies. Not a one. The closest thing would be Ridley Scott's Gladiator.