Realtime map of lightning strikes JUN 23 2014
This map showing where lighting strikes are happening right now is kind of great:
Average delay is about 3-5 seconds. Make sure you turn the sound up too. That's the North American map...there are also maps for Europe, Asia, Australia, and South America, although only NA, Europe, and Australia seem to have detectors in place.
The detection system is volunteer community effort. Anyone who wants to can buy a detection kit (for around 200 Euro) and hook it up to the Internet to provide strike data. In turn, the data collected from stations is made available to any station owner. See also the wind map of the Earth and the realtime map of global ocean currents.