A strong grip will get you far in this world. No more limp handshakes for you-- hellooooo business deals! Or, say you slip off a cliff. You can grab onto a branch or a rock and pull yourself back up! Heavy groceries? Nah, you won't need help carrying those. Or maybe, like me, you just want to lift heavy stuff, just because. Whatever your reasons, a strong grip is a good thing to have.
I have spent the better part of the last two decades trying to get as strong as possible, and while I have a long way to go yet, if there's one thing I've learned it's that grip strength is essential for overall lifting strength. Here are some exercises I love that help build grip strength (and plenty of other muscles, too):
1) Thick bar anythings. I'm a big fan of thick bar lifting. Anything you use a bar for, just wrap a towel around it and make it thicker. This is an instant grip challenge, as you will not be able to wrap your hands around the bar as easily as you're accustomed to. The more times you wrap the towel around the bar, the harder the lift will be. Here's an example:
While the towel is the cheapest way to go with this (I assume you already own a towel, or know someone who does), you can also go the PVC pipe method (get a thick pipe, and just hang some lifting chains off the sides of it, fill the thing with buckshot or water or whatever you want to weigh it down with, etc). A simple bar pad, like this one, will work, too: http://www.amazon.com/Valeo-VA4541BK-Bar-Pad/dp/B0007W2EPK , and you can even use pipe foam: http://www.amazon.com/Thermwell-Products-Foam-Pipe-Insulation/dp/B000BQY9Z0 There are also a couple of other, more expensive, fancy-shmancy options. You can buy an actual thick bar (like this one: http://www.functionalhandstrength.com/black_iron_strength_thick_bars.html ) or you can buy Fat Gripz (or similar): http://www.fatgripz.com/ .
2) Hanging Out. Just hanging from a pullup bar will give you some pretty impressive grip strength. Most people will find that their grip gives out before anything else when they do hanging exercises. You can increase the difficulty of a dead hang by switching to a hook grip (no thumb), adding weight (with a weight belt or hanging a kettlebell off your foot), and, as above, increasing the thickness of the bar.
A tool a lot of climbers use to increase their grip strength is a hangboard: http://www.nicros.com/archive/archive18.cfm . Hangboards are great for finger strength, but are definitely a skill to work up to if you're just beginning.
While we're on the subject of pullups, doing towel pullups is a great grip strength workout. To perform a towel pullup, you'll loop a towel over a bar/branch/whatever, and do your pullups using the ends of the towel. It looks like this:
3) Farmer's Walks. I'm a huge fan of heavy farmer's walks. All this entails is one or two kettlebells, dumbbells, buckets filled with water, etc. You just pick them up, letting them hang at your sides, keep your back as straight as possible, and walk around with them till your forearms scream. It's amazing for the core as well as the grip, and doing a one-armed farmer's walk challenges your body in a much different way from a bi-lateral farmer's walk. If you'd like to see a video of a farmer's walk, here you go:
4) Hook grip swings. Take your average kettlebell swing, and take your thumb off the bell handle. This will take away the "crutch" your thumb provides and will force you to rely on your fingers for gripping. Some people like to lotion up their hands and swing that way; if you go this route, I highly recommend finding a big, open, outdoor area where you can be sure no one and nothing will get hurt by a flying kettlebell.
This is really only scratching the surface of grip training exercises, but it's a good place to start.
Questions? Comments? Suggestions? Post 'em here!