Blitzortung.org is a lightning detection network for locating electromagnetic discharges in the atmosphere (lightning discharges) with VLF receivers based on the time of arrival (TOA) and time of group arrival (TOGA) method. It is a community of station operators who send their data to the computing servers, programmers who develop and/or implement algorithms for locating and visualizing of sferic positions, and people who assist in any way to keep the system running. There is no restriction on membership. All people who keep the network in operation are volunteers. There are no fees, terms and conditions, and no contracts.
Check out my detectors and some lightning maps.