I just finished my review of Zacuto's Z-Drive and Tornado Grip over at Pro Video Coalition. This is an out-of-the-box product that cleverly blends a follow focus and hand-grip together. Together, the Z-Drive and Tornado let an operator pull focus while keeping a shoulder-mounted camera rock-steady.
I had a chance to work with the Z-Drive/Tornado Grip on a few projects, and added it to my own kit because it genuinely gave me better results in shoulder-mounted camera work, and also kept things more comfortable. You can read the review right here.