iPhone: The Missing Manual, 3rd Edition

Nike + iPhone 3GS

Here's what you might consider an unlikely partnership: Apple + Nike. For $20, you can buy a tiny Nike/Apple transmitter that you slip into a special socket in specially marked Nike running shoes. (Pssst—you don't actually need the shoes. Online, you can buy a cheap little Velcro pouch that fastens the transmitter to any old shoe. Or just stick the transmitter in your sock.)

Then, as you run, you could listen to your workout playlists; in the background, the software displays your time, distance, pace, and calories burned. It even talks to you—for example, letting you know when you were halfway and near the end of the run. After each run or walk, you can upload the data to Nikeplus.com to track your progress, slice and dice your statistics, compare workouts with other people, or even challenge them to a virtual race.

(Don't buy the $30 Sport Kit by mistake. It includes another part—a snap-on iPod receiver—which the iPhone 3GS doesn't need.)

To get started, you have to unlock the dormant Nike feature. From the Home screen, tap Settings. Scroll wayyyy down the list until you see the cluster of settings for your individual apps; one of them is Nike + iPod. Tap to turn this feature On. Now the whole screen of Nike + iPod settings appears:

• PowerSong. A PowerSong is one particularly motivating tune that you can summon (by tapping PowerSong) as your willpower to keep running begins to fade. ("I Will Survive," perhaps?) Tap here to open your master iPod song list, where you ...