Intel researchers, in conjunction with the University of Washington have developed the Wireless Identification and Sensing Platform (WISP). A WISP is a standard RFID tag with the unique inclusion of a 16-bit general purpose microcontroller that supports sensing and computing. Like any passive RFID tag, the WISP is powered and read by a standard off-the-shelf RFID reader, harvesting the power it uses from the reader's emitted radio signals to operate the microcontroller. One application of WISPs could be to monitor temperature, moisture, light and more in a building. This information could then be used to enable finer HVAC control thus leading to a more efficient building environment. More info at Intel.