This Warhammer Google Map includes all provinces of The Warhammer Empire, including Bretonnia, Estalia, Tilea, The Border Princes, Norsca, Troll Country, The Dark Lands, The Worlds Edge Mountains, Albion, The Badlands and Araby.
The map includes a useful measuring tool that can calculate the time it will take to walk between two points in the game.
Grand Theft Auto IV - Custom Street View
This awesome Google Map lets you explore the whole of Liberty City, from Grand Theft Auto IV, in Street View.
GTA4.net have created custom Street Views of the whole of Liberty City and added them to this Google Map. The map shows all the important locations in the game, such as health & weapon pick-up points and all the important mission starting points.
There are a few websites devoted to helping you create custom Google Maps of your Minecraft worlds. Tectonicus is a great minecraft map renderer that can help you create map tiles of Minecraft 3D worlds for Google Maps.
I like this Minecraft map from Köttdisken because it includes a few custom made Street Views of the mapped Minecraft world.
World of Warcraft Map
This Google Map created for World of Warcraft includes quick links to common locations and options to show the locations of herbs, treasure, ore and other game elements.