Turn an object's shape keys into cloned objects, optionally with modifiers and vertex groups removed.
The clones are named <name>_<shape key> and their data are named <name>_<shape key>Shape
With an object selected, press F3 and choose Create duplicated objects for each shape key.
Select "File -> User Preferences" and choose "Addon" tab. Click "Install from file..." and choose the downloaded file (only "shape_keys_to_objects.py", not the folder).
For Blender 2.9 make sure "Edit -> Preferences -> Interface -> Developer Extras" is checked. Blender 2.91.2 onward does not require this step.