You might also check out our page on Hand Exercises, which you can find at:
Hope this helps!
If you sit down on the end of a bench with a dumbbell in your hand and your forearm on your thigh, you can do forearm dumbbell curls. They are even better if you let the dumbbell really go down a long way so that your grip loosens on the dumbbell a little bit and your fingers extend a little bit.
You might also try thick handle training, whether it is a barbell or dumbbell. When you lift a dumbbell with a thick handle, your fingers have to work REALLY hard just to hold the weight. I love training like this.
Here is an easy idea for you that sounds really stupid but works really well. It is harder than you think.
Go to a pullup bar or an I-beam in your basement with a "lip" on it. Grab on and put your feet in the air so you are hanging. Now just hang there for as long as you can. Start with trying for 3 minutes. Good luck with even that especially on an I-beam. If your forearms look like POP-EYE you can do it for 5. Feel the burn!!!!!