Due to my lagging grip strength, as well as my desire to hit up as many muscles in my body as possible, I started to throw in a small number of direct forearm sets and dedicated an entire day to arms. I do 2 sets of wrist curls, and 1 set of reverse wrist curls. As well, for a small additional amount of work, I threw in a single set of hammer curls and two sets of straight bar curls when doing biceps.
My forearm strength has shot up dramatically in just a few weeks. Just this past week my wrist curls went from 75 pounds 11 times to 85 pounds 10 times. As well, I went from 55 pounds for 7 reps to 10 reps on the reverse wrist curls. On top of this, my grip strength has definitely improved. In addition to being able to last longer and go a little heavier on lifts like deadlifts and SLDLs (The real reason I started to notice my lagging grip strength), my grip feels more solid and in control for any heavy lift. I don't know if I have gained much mass, but strength is really what I care about anyway. Plus, I've only been directly hitting the forearms for about 3 weeks now.
Just felt like I'd throw in a little useful information for those looking to increase their grip strength. I hope I'm not the only one who's had trouble with that.