Useful gadgets in the self-tracking or quantified self movement include:

• Fitbit ($100) monitors movements while you sleep and counts your steps; it sends all the data back to Fitbit’s Web-based tracking program, which displays your activities on precise charts and graphs.
• MyTrek, a wireless pulse monitor made by Scosche,
• Withings WiFi Body Scale, an electronic scale with an Internet connection that displays your weight.
• A blood-pressure monitor by Withings that works with the iPhone, iPad and iPod Touch.
• Exergen TemporalScanner, a thermometer that accurately measures your baby’s temperature.