Right now, I can't really push the weights, so I dug out some grip tools that I hadn't used in a while. If you've never been bitten by the "grip training bug", then you don't know what you're missing.
Ironmind has a number of specialized grip training tools and they're one of the oldest in the business of "fringe" strength training (which isn't so "fringe" anymore by the way). The Captains of Crush grippers are a lot of fun and I bought a "trainer" and "No. 1" about 10 years ago. Like a lot of people, I was crazy about them for a short stint and overdid them to the point of developing minor tendinitis - I'm not recommending that approach.
One of the lectures that sticks out from the RKC Certification was Brett Jones and Mark Reifkind talking about the hips and grip being "neural potentiators" - which is absolutely correct. My father always used to (and still does from time to time) mention how the Russians did studies measuring grip strength and found strong correlations between a lifter's measured grip strength prior to an Olympic lift attempt and their success or failure. The grip, is at the end of the strength chain - if you can't hold on, it won't matter how strong your core is.