This is a 'fun' project intended to solve a problem without using a microcontroller.
The problem: My elderly housemate will walk in complete darkness into the washroom at night, and the current night light does not provide adequate lighting along her path. Thus some LED strip along the floor to light the path and under the ledge to illuminate her grab bar required some switching.
The solution: A standard PIR sensor is coupled with a photoresistor and 555 timer, along with some transistor level logic glue and turny knobs, switches on the safety lighting only when the room has reached the specified darkness. Brightness is also adjustable, while a three way switch toggles between steady on, light/motion switched, and off.