Teeny, tiny floating lamp. Taking a design cue from the 9-Volt Battery, the 9-Volt Light mimics and floats atop its power source. The design by Richard Lawson was the loser of Mathmos' design contest. (The same Mathmos that invented the lava lamp.) However, they liked what they saw and decided to manufacture the tiny lights.
The LED lights are white when off, and shine in red or blue light when connected. We'd guess the illumination would be the equivalent of a small candle. But be forewarned they aren't cheap. If you have visions of filling your next outdoor party with these little guys, you'll need a nice bankroll. At $25 each, these might not be in your budget.