The Google Maps Mania blog has a roundup of maps of Westeros and Essos from Game of Thrones mostly built in Google Map platforms.
Game of Thrones is an Esri StoryMap of Westeros and Essos. The map sidebar includes links to important locations on the two continents.
The Interactive Game of Thrones Map is a Google Map of the fictional continents of Westeros and Essos from George Martin's series of fantasy novels A Song of Ice and Fire.
The Westeros Map is another Google Map of the fictional continent of Westeros
Arya's Journey plots the story of Arya Stark,the youngest daughter and third child of Lord Eddard and Catelyn Stark of Winterfell.