Nokia researchers are developing software to turn cellphones into lightning warning systems. The RF receivers in cell phones can detect the radio waves emitted by lightning, and the distribution of the signal can indicate the closeness. From New Scientist:
The multiple receivers in a phone, such as Bluetooth, FM, tri-band GSM, Wi-Fi and RFID, can be tuned to pick up these signals, says Nokia (US patent application 2007/0085525). Software will then interpret them, work out the distance to the lightning, and tell you if strikes are getting closer.
Link to New Scientist, Link to US patent application
