Interactive aquarium full of bioluminescent plankton called dinoflaggelates ("dinos"). The plankton illuminates the dinosaur-shaped environment when you gently shake it. Just let them bask in indirect light during the day, and they'll treat you to a soft
LED ribbons integrated into stairs. Late at night, the stairs can be lit (and safe) without ruining your night vision with bright overhead lights. Would also be a great way to really highlight a gorgeous staircase. @ Home Renovation Ideas
Smart thinking - to counteract the feeling of being below ground level, add cabinet doors with frosted glass over window well windows. A fluorescent light is behind each one, so that when they are on, there is light coming through day or night.