Sound maps may not be a well-known or popularized tool, eclipsed by its visual counterpart Google Maps and its kind. However, there are serious sound map projects underway.
Sound Around You is a research project from University of Salford which allows everyone to help build a sound map of the world using a mobile phone. To contribute, you may get the app isay for iPhone, iPad or iPod or use your own recorder to capture, comment on and upload your day-to-day sound environments. Your soundscapes and opinions will then be anonymously placed on the world map. This worldwide soundscape research project utilizes crowdsourcing to collect description of sounds perceived by people around the globe and have perception evaluated in scale, exemplifying collective endeavours in sound mapping.
Details at: http://www.soundaroundyou.com/
London Sound Survey is a growing collection of sound recordings of people, places and events in the capital of the United Kingdom. The survey divides London in a grid of squares and makes summary of its soundscape by plotting in outline the common or persistent sound types heard around London during the daytime. The recordings concern mainly the background atmospheres and incidental noises from all over London.