Two hot new tools  for self-tracking were introduced at the recent Quantified Self conference:

A device from a startup called Basis that looks and acts like a watch, but which also measures heart rate (using near-infrared spectroscopy), skin and ambient temperature, and galvanic skin response (sweating, with high heart rate and temperature, probably means someone is exercising).

Stickers with an embedded accelerometer and an ultralow power wireless transmitter from startup Green Goose for use in games that reward healthy behavior.