Stamen Muzei combines two wonderful free services, Stamen Maps and Muzei.
Your background will be regularly updated to feature a map centered around your current location. If the forecast calls for rain, that map will be dark and black (toner), while in all other cases, your map will be pastel and light (watercolor).
• Install Muzei (https://play.google.com/store/apps/details?id=net.nurik.roman.muzei)
• Open Muzei app
• Select "Maps" as your source
• Enjoy beautiful background maps as your background
Stamen content is licensed under CC 3.0 : http://creativecommons.org/licenses/by/3.0/