3D Color Picker places its own GUI in the Blender 3D viewport. Pickers, shown as colored balls, sit inside a cube-shaped Palette where each XYZ axis represents HSV: moving a picker along X adjusts hue, along Y adjusts saturation, and along Z corresponds to lightness. In the current version this applies to the Base Color of the Principled BSDF node in Material mode, and the colors of lights can be adjusted too. Several materials can be manipulated at the same time.
The Shaker feature generates random color combinations with a single click. Its Replace function lets you specify a range of random values for hue, saturation and lightness individually, and request light, dark or bright combinations. The Offset function adds a small random number to the current combination, which helps fine-tune a set found with Replace.
Built by IYOYI, the add-on is released under the GPL license and supports Blender 3.3 through 3.6. A demo video is available on the developer's page.