Tie your **** to a barbell and try to straighten your legs. This is effective for both lower body strengthening and ***** enlargement, apparently. In all seriousness of course deadlifts etc will improve grip strength, my bad.
I was taking a sports medicine workshop a while back and one of the assignments was to buy some reusable clay and play with it (to see what arises, it helps work through dormant tensions in the body associated with the hands/ fighting syndrome), I found 5 minutes playing with clay produced significant new sensations in the hands to work with during boxing classes. Id reccomend working with clay, or at least trying it for a weak. Clay is very cheap, it would cost you max 5 bucks.
Rope climb is (IMHO) number one vertical pulling exercise. But only when pulling with your arms with your body in a l-sit position.