Nightlights that are charged by the sun. The solar tube concept is proven and fully excellent already, I just want to improve it one notch. The sun comes down a mirrored tube from the lens on the roof and lights up a room with beautiful natural sunlight, even down to the basement. The end of that tube is a diffuser. That diffuser could and should be laced with glow stuff, the phosphorescent glow-in-the-dark material that we know and love. It could charge up all day while still letting the right amount of light in, then continue casting glow-light for 2 hours more. Totally doable, yo. To quote my man Beck, Hell Yes.
To quote my man Obama, Yes We Can.