Adafruit Industries has released a necklace companion to the pulsing iCufflinks. The iNecklace is a CNC machined aluminum pendant with a pulsing LED that glows like the sleep-indicator on MacBook Pros.
The necklace pendant is CNC machined from the finest 6 series aluminum for durability and beauty. The iNecklace is a remarkable accessory. Machined with a "screw in backing" that allows easy access to the battery using a coin. Each iNecklace pendant contains a circuit board with pulsating LED and battery. The pendant comes strung on a 18" long sterling silver 1.6mm diamond-cut curb chain that has been treated to inhibit tarnishing.
Like with the iCufflink, the iNecklace emulates the pulsing LED in Apple's sleep indicator, an Apple patented technology that Adafruit reverse engineered. Apple found that the by mimicking human breathing for their sleep indicator, it was more "psychologically appealing and superior" to other waveforms.
Adafruit has a limited supply of the iNecklace available for $75. The iCufflinks are $128 but currently out of stock.