http://www.prohands.net/who/sports/handgun/index.php I looked at this product for a long time and finally ordered on for myself and one for my wife, for the reason to retrain my grip on the weapon and to improve my shooting abiity, by improving my grip. I thougt you might like to check it out for yourselves.
I saw one of these at my local gun shop and played with it. Interesting and different, but not something I'd spend money on. I've been using a Tennis ball for years to strengthen my grip, and there's no reason to change now.