There are plenty of things to do....
depends what you want from your hands.
there are many ways to train different aspects of hand strength
I try and fit some work in with thick handled dumbells (even if its just bicep curls) I bought an extra set of dumbell handles (i train at home) and wrapped a whole lot of gaffa tape (sorry i dont know what you call it in america) to thicken up the handle
I also built a wrist roller. All it is, is 1 foot of curtin rod (i have a thinner PVC pipe as well) Just drill a hole half way up the rod, and thread some thin strong rope through. and
I used to do some "pinch gripping" but i dont have enough time for it (when i quit my job maybe!).
I also use a weighted stick to build up my weak wrists.
All i use is a shitty plastic bar that i found...its like 2 or 3ft. I load up only one side with 5-7lbs. I hold the unweighted end and with my arm to my side and lever the bar in all different directions.....
I HOPE I AM MAKING SENCE!
Here is a page on ironmind
http://www.ironmind.com/griptip.shtml
Its written by john brookfield.
he has a good book on handstrength that can be purchased on the site.....but on the link....if you click MORE there are some mad ideas.