Revo Lights

What originally started as a Kickstarter campaign has now become a full fledged little company.
Revolights don't just light your path when cycling, they also make you more visible to other traffic in all directions.

Transparent OLED Light Source

The transparent hexagons in the roof of this Smart concept car are actually also light sources illuminating the interior when it's dark. A transparent layer of OLED's can be turned on to emit light when needed. The video is heavily loaded with propaganda for BASF, but the idea is sound in my opinion.