(Many Colors Available) Mivizu Nike+iPod Shoe Lace sensor Pouch for Nike + iPod Sport Kit compatible with iPhone 3G S / 3GS
This is a neat little doo-dad that has helped me utilize the Nike+ app on my iPhone 3GS. It tracks how fast you are going and reports it directly to the app on the iPhone. The size is right as well as the price, but the inability to easily move this from shoe-to-shoe could be a dealbreaker for some and it definitely was for me. I ended up getting a GPS based watch and ditched the foot pod all together. No clutter on my running shoes now.