This video depicts a bunch of people in Brazil who light their homes with plastic bottles of water wedged through holes in the roof. The water acts as a reflector, bouncing the daylight all over the room. In the video you can see them popping black plastic film cannisters over the lids of the bottles- they do that because that type of bottle comes with a cheap lid that cracks when exposed to sunlight for too long.
Each bottle gives off about as much light as a 50w bulb, reduces energy use, and is a clever way to divert those bottles from becoming waste. This whole idea made me really happy.