London Sound Survey - a site dedicated to collecting the sounds of everyday life around London - has published a short guide to creating sound maps.
The idea of a sound map is to associated geographical information with an audio file, much like some digital cameras can now geotag photos.
An example sound map is embedded above. Note that it is interactive, so you can explore both the map and the audio files assocated with the map.
Details at the Sound Survey site.
Gaz Williams has one and he brought it round