Let me introduce a Boy - Animation Character Rig made in Blender
I've made it to demonstrate all the rigging and scripting techniques & approaches I am familiar with and that I use in my work trying to create something animators will be happy to work with.
This is fully rigged animation character with UVs and packed textures, it has FK and IK chains for all the limbs and each chain is stretchable and has additional tweks (tweaks affect bendy bones rotation and roll).
Limbs also have extended fingers controllers (bend and spread actions, actions for each finger).
Body mechanics is much more advanced then the average animation task needs (multiple tweaks, IK chest, adjustable space for FK and IK limbs controllers).
It also has facial rig with multiple actions (blinking, emotions for eyes, brows, mouth) and functions (eye ball response, cheek response).
Rig has squash and stretch for both head and entire character.
Also you'll find very handy custom panels (made with included in .blend file Python script): armature layers, bones selectors, rig properties for selected bones / all bones, IK-FK snapping for selected bones / all bones.