B&W P5 Headphones
As with all of its products, B&W employed the best possible materials and technologies in the P5. The drivers consist of optimized Mylar diaphragms with ultra-linear neodymium magnets, and the cable is cleverly routed around the driver in a channel under the removable earpads, which are made from New Zealand sheep leather. B&W claims that the earpads are noise-isolating while allowing just enough ambient sound to provide a sense of place, but being on-ear instead of around-the-ear, I can't see how they provide much isolation.
The P5 comes with two interchangeable cablesone with a standard jack for any MP3 player and the other specifically for the iPod and iPhone that includes a microphone and control for volume and track selection.
At $300, the P5 is relatively expensive for portable headphones, but a mere pittance compared with most products I profile here. Still, the design is so cool, I decided that the P5 definitely qualifies as ultimate gear.