Client Libraries
Client libraries to simplify access to the GeoNames 
web services exist in a couple of programming languages.
Tools
Plugins
Frameworks
-  Gisgraphy: an open source framework for GeoNames data, with importer, geolocalisatoin and fulltext search.
 -  NGeoNames:.Net package. provides classes for downloading and parsing files from GeoNames.org and provides (reverse) geocoding methods like NearestNeighbourSearch() and RadialSearch() on the downloaded dataset(s).