I have recently started a campaign with myself where I do pull-ups first thing in the morning before really even being fully awake. I climb out of bed, walk down to the basement and do two to three sets of ten. I bought Fat Gripz and I put them on my pull-up bar.
When I first started doing them I coulnd't hang on long enough to do ten pullups. I would have to set down my feet at about 6 or 7, and re-grip before finishing the set. Now I do ten and then hang there for a ten count. I haven't had any compliments on my grip strength yet, but I plan on keeping up with this. In fact, the reason I am posting in this thread right now is because I just ordered the Orange Extremes on Amazon and I eagerly await their arrival now.
Anyways my original intention was to use the Fat Gripz for everything I did on the gym, so I bought two original blue sets (I have two gyms in two cities I work out at) so I could use them all the time. However I think my ego was the thing that stopped me from using them because can't lift nearly as much with the Fat Gripz on the dumbbells. I know that's lame but I am just being honest. Really I should buckle down and use them all the time like I originally intended but I haven't yet. I know there is a curve with these things where you have to decrease your lifting weights for a while but then you return to those weights with even more strength, supposedly.
Anyways, the orange ones are pretty much going to be exclusively for pull-ups at home, and the blue ones I will take with me to the gym from now on, etc. I am hoping it helps because my grip strength is lacking.
Edit to say that one of our really good Purple belts, Tim, and my Instructor Stew really encourage kettlebell exercises for gripstrength training as well. They also encourage people to hang a Gi over a pullup bar and do pullups with Gi grips, if you roll Gi.
I don't have kettlebells at home so I chose the Fat Gripz.