I came across an ad on Facebook a couple months ago for a company that makes palm grips designed to protect your hands from tearing, ripping or developing ugly calluses while working out.
The company's called GriPad and I sent them an email and asked if they'd be interested in sending me a pair so I could try them out. My hands have always been pretty rough and I've had calluses since I was a kid so wasn't too concerned about the protection they offered but thought the grips might help me make some gains on a few exercises like weighted pull-ups, barbell deadlift and bent over row.
I've had the grips for a few weeks now and have tried them out about a half a dozen times with a few different exercises. For me, they work really well for low rep, weighted pull-ups, lat-pull down, bent over dumbbell row and seated cable row. They give me a much stronger grip on the bar and allow me to focus more on the muscles I'm working (lats, rhomboids, rear delts) rather than thinking about my grip.
The two exercises they didn't really help me with though were high rep pull-ups and the barbell deadlift. With the high rep pull-ups, the Gripads helped to save my hands from tearing but once I started to fatigue, I had trouble re-gripping the bar. If I didn't have the grips on I could have re-adjusted my hand position on the bar and squeaked out a few more reps. With the barbell deadlift, I wasn't able to get a good enough hook grip on the bar with the Gripads on, I still prefer just using chalk.
All in all I think the Gripads would be an excellent addition to any gym bag! I used mine yesterday during my workout, I've been using them with several of my clients and I've had a few other trainers in the gym ask to borrow as well. The grips are relatively inexpensive, I think about $15 a piece, and come in a wide variety of colors!