To build your forearms and grip strength, you need to train all three grip functions: support, crushing, and pinching strength. This exercise will take care of the last two categories.
These build significant functional strength and hypertrophy throughout the entire musculature of the forearms, not to mention Herculean grip strength. Note the pause at the top and bottom of each rep.
Other exercises include: fat grip lifts, plate pinching drills, towel pull-ups, rope climbing, rope pulling, and hex dumbbell pinching exercises. (More info here: Freaky Forearm Training.)
Dave Tate is the co-owner of Elite Fitness Systems and has been involved in the sport of powerlifting since 1982. A true testament to his skills rests in the 10,000 hours of personal training and strength consulting sessions he has performed with novice to elite athletes. Numerous clients have broken barriers they never thought possible through the use of maximal, dynamic and absolute strength development methods.