Credit Card Sized Lightbulb
Well hello novelty, at least according to one commenter on the linked product page. The LED Credit Card Pocket Light is small enough to fit into a wallet and uses a 3V built in battery to power its light source – not sure how you recharge it, though. My mom might enjoy this product for reading menus in dark restaurants, but beyond that its practical applications have to be few and far between.
Meritline currently has it on sale for $3.99 including shipping.