Just this morning when I was browsing for some temples over wikimapia as usual, I was going across Pazhamuthircholai, one of the six big temples (padai veedu) of Lord Muruga and I was stunned. The satellite view of the place shows a clear and perfect natural formation of divine's spear (vel) on the rocks. I would not have noticed it but for the matching manual marking of the temple by somebody (even he/she might not have noticed it since nothing about it is written in the description) as shown in the 2nd picture.
You might have already seen a similar one in my Avaniapuram travelogue - A natural rock formation of lion at Avaniauram Narasimhar temple hillock. Avani meaning lion and apart from Narasimha perumal, the thayar also has a lioness face. http://shanthiraju.wordpress.com/2009/04/28/avaniyapuram/