Dimmable Nightlight shown as part of a duplex
Cooper Wiring Devices has an option for a built-in nightlight. The nightlight can be stand alone or installed as the top half of a duplex or switch installation. It is part of their Patrol series which you can read more about here. Along with the standard nightlight applications, this can be installed in stairways, basements or garage areas which are notoriously dark when the main lights are off. In standard living areas they feature a light-level sensor that turns off the nightlight when there is available daylight or other sufficient ambient light. For convenience they have three preset light levels.