Google Maps' Moat
Many people don't realize why Google maps are so much better than anything out there. I would actually give lot of credit to Marissa Mayer who suddenly became in charge of maps from otherwise more higher position. Thanks to her influence in Google SLT and ability to make impressive arguments, she was able to make a case for maps as core pillar in Google's offering and consequently obtain huge investment and large talent pool to work on it. Creating these level of details world wide requires dazzling amount of investment that even some small governments can't afford. In most companies, you will not get green lighted for this because there is no real revenue coming in and its basically social charity in form of a free app. Now the reality is that you can't do self-driving cars without great maps and the day Google pulls its map app from iOS you can bet Apple is going to have a giant hole in their balance sheet.