Straps and hooks for protecting your palms and/or increasing the amount of weight you can lift.
Straps are a popular way to lift heavy weights when doing deadlifts. You slip the straps around your wrists, wrap them around the bar, and grip the straps covering the bar instead of the bare bar itself. This serves two purposes: protecting your hands from damage and making it easier to grip the bar when lifting heavier weights. Most people find that their max lifts are higher with straps than without, indicating that their hand strength was the limiting factor.