Originally Posted by aerodyne1989
Get on eBay and buy yourself a gripmaster. They're great for dexterity and overall keeping all your hand wrist and finger muscles in shape.
OP, dont waste your money on these gadgets. They have no use where bass playing in concerned as they develop grip. The first thing a teacher will tell a student is to play with the hands relaxed. This is impossible when you grip. Besides, you only need minimal strength to fret a string. This strength is naturnally there from a very young age, so developing grip is not required.
A far better idea is to try fellow TB'er Fergie's solution here : http://www.youtube.com/watch?v=Ab-dtzrAnkg