I have now seen it all - a Darth Vader rubber ducky!
Naturally, I had to buy one.
"The I-Duck has got to be THE 'must give' present. It comes in eleven great designs, Pink, Blue, White, Yellow, Green, England, Ducktor Who, Proud, Duck Fadar, Lover, and the cute I-Duck Nano. They all have a self contained battery which powers the internal LED's when they are placed in water. The duck has two small contacts in its sealed base, which are shorted, causing the duck to light up. When it lights up, the LED's changes through a wide variety of colours over a 45 second cycle. Each duck comes in its own colour designed presentation box, which makes it an ideal gift. PLEASE NOTE: The battery lasts approximately 40 hours, but unfortunately cannot be replaced. "
Many thanks to Dale for pointing this out to me!