Is there a web service that provides terrain type at lat/lon?

I'm wondering if there is a (free?) web service that will return the type of terrain at a specific latitude and longitude?

The most important data I'm interested in is whether the point is over water or over land. It would also be useful if I could find out if the point is in an urban area, desert, or in the rainforest, etc. I might be able to guess that based on开发者_开发百科 average rainfall/temperature for a location, or doing a reverse geocode.

Check out GeoNames database, 7.5 million locations including lat/long/elevation and type of each location (see dictionary here).

I don’t know any ready-to-use web service, but I imagine you could use data from OpenStreetMap; if you are only interested in large bodies of water (e.g. be able to distinguish points in ocean), even the small png2tileinfo file would be enough (having 2-bit information for every ~0,088° square). Otherwise, the whole rest of the precise data is available there, but some preprocessing of the huge amount of data would be needed.