Web API for reverse geocoding geographic features

Question

Is there a free web API that can reverse geocode geographic feature names? I'm currently using the Google API, which will return political and street address info, but I would like to return the names of mountains, islands and especially bodies of water for a given lat/lng pair.

Answer 1

Reverse Geocoding Webservices from geonames

"Reverse Geocoding" is the process of finding an address, toponym or an other type of resource for a given lat/lng pair. GeoNames offers a wide range of reverse geocoding web services.

Find nearby postal codes : finds postal codes and place names for the given lat/lng within a given radius. (supported countries)
Find nearby place name : finds pouplated place names for the given lat/lng within a given radius
Find nearby : finds any toponym for the given lat/lng within a given radius
extended Find nearby : most detailed information for toponym for the given lat/lng within a given radius (combination of 4 services)
Find nearby Wikipedia articles : finds wikipedia articles for the given lat/lng within a given radius
Country : finds the ISO country code for the given lat/lng.
Country Subdivision : finds the country and the administrative subdivison for the given lat/lng.
Ocean : finds the ocean or sea for the given lat/lng.
Neighbourhood : finds the neighbourhood for the given lat/lng (US cities only).
Weatherstation and weather observation : finds weatherstations and most recent weather observations for the given lat/lng. 

US Street level reverse geocoding services :

Find nearest Address : Finds the nearest street and address for a given lat/lng pair. (US only)
Find nearest Intersection : Finds the nearest street and the next crossing street for a given lat/lng pair. (US only)
Find nearby Streets : Finds the nearest street segments for a given lat/lng pair. (US only) 

Global Street level reverse geocoding services (cc by-sa license):

Find nearest Intersection : Finds the nearest street and the next crossing street for a given lat/lng pair.
Find nearby Streets : Finds the nearest street segments for a given lat/lng pair. 

Others :

Timezone : returns the timezone at the given lat/lng.
Aster Elevation : returns the Aster elevation (30mx30m).
SRTM3 Elevation : returns the SRTM3 elevation (90mx90m).
GTOPO30 Elevation : return the GTOPO30 elevation (1Kmx1Km).
Points of Interests : returns nearby points of interests (cc by-sa license) 

http://www.geonames.org/export/reverse-geocoding.html