Bone Widget is a Blender add-on that assists with creating custom bone shapes. It comes with an editable library: many shapes are pre-made and ready to apply to any rig, and you can add your own shapes to the library as you build out a rigging setup.
Starting with version 2.2, the add-on also manages bone colors in Pose Mode, and in Edit Mode if you enable that in the user preferences. Blender normally handles bone colors through 15 predefined Bone Color Sets, five blank ones, the default colors, or a custom color set, and Bone Widget lets you work with these alongside your own custom colors. It can also display different colors for Edit Mode and Pose Mode.
On the Blender Extensions platform it sits at popularity rank 227. Bone Widget is compatible with Blender 4.2 LTS and newer and is distributed under the GNU General Public License v3.0 or later. A demo video is available.