Reset All Shape Keys Hotkey handles a repetitive part of Blender animation: zeroing out the shape keys on a selected mesh. The addon resets all shape keys in one action, and you choose whether or not to keyframe the zeroed-out values.
Control over which keys get touched is built in. You can tell the addon to ignore any shape key already sitting at a value of 0, pick individual keys to bypass, or bypass keys based on their position in the list. The reset button lives in the 'Tool' tab, and you can assign a hotkey to it to speed things up.
According to the developer, the addon is extra useful for shape key facial animation and for mocap cleanup. It's licensed under GPL and lists compatibility with Blender versions from 3.0 through 4.3. A demo video is available on the developer's page.