"The After-Lite is a plastic-based disc that hooks up to the bottom of an energy-saving light bulb, and whenever you turn your lights on, the disc will “charge up”. Turning your light off will allow the After-Lite disc to glow (much more brightly compared to those glow-in-the-dark stickers) to help you find your way around at night without spending a single penny on electricity." - Victor Ryden 美久太阿 from Bookmarklet

After glow would have been a better marketing name ;) - RAPatton