The inverted row isn't just for beginners. More advanced lifters can use it to build massive forearms and crushing grip strength. Just use a thick bar or Fat Gripz attached to a regular bar.
Set up a thick bar in a rack or use Fat Gripz.
Get a good grip on the bar, pull, and pause for 1-2 second count at the top.
After 7 or 8 reps, you'll really feel it. Ramp it up by wearing a weighted vest if needed.
A bar takes the ab rollout to the next level. Try a wide grip to hit the chest and shoulders as well as the abs. Have a super strong core? Narrow the grip.
The most underutilized pieces of equipment in most gyms are the dumbbells. Oh sure, you might see people pumping out a few sets of biceps curls, bench presses, or flyes, but in most gyms the dumbbell racks are primarily used as a place to lean against between sets of barbell squats or benches.