Bye-Bye, Batteries - Radio Waves as a Low-Power Source

This deserves more attention.

Ambient radio waves can already provide enough energy to substitute for AAA batteries in some calculators, temperature and humidity sensors, and clocks.

The NY Times article discussed one way to harvest ambient energy. Some companies have been doing it for years. See also: Energy Harvesting Journal, Alternative Energy, this Science Daily article, Energy Harvesting Forum, and Wikipedia's Energy Harvesting article.