[EDIT] In this thread, there may be broken links as time goes on. The purpose of the posts is to give members ideas to build on and be a repository for other people to add to as well. Happy building! Oh, let me add that I have no affliation to any seller or company. Always check out your suppliers before handing over your hard earned cash.

Well its new to me. I can see it now. "Dave, there seems to be an approaching storm. It's time to stop our soccer game and get inside" eBay Link, Datasheet Link

Franklin Lightning Sensor provides early warning indication of lightning storm activity within a 40km range

• Provides distance estimation to the head of the storm
• Detects both cloud-to-ground and intra-cloud (cloud-to-cloud) ashes
• Intelligent algorithm provides for false disturber rejection
• Programmable detection levels enable threshold setting for optimal con gurability
• SPI and I2C interface is used for control and register reading
• Automatic antenna tuning
• Supply voltage range 2.4 to 5.5V
• Power-down, listening and active mode

Here is another one for motion detection for up to 20 meters. eek Microwave Doppler Radar Motion Sensor

Edit: see post #6 for better one.

UPDATE: Here is another lightning detector that popped up. eBay Link