Blitzortung.org is a private network of lightning tracker stations. They catch the electromagnetic signals of strikes.
Together with the timestamp the position of a strike can be calculated out of the signals (TOA - time of arrival method).
You will find more information on the main site of the project: www.blitzortung.org
Accuracy is quite good and is sometimes lower than 1 kilometer. This is equal to commercial strike detection companies.
You have to build your own receiver (costs about 200 Euro). With that, you can participate in the network and you will get access to all strike data.