http://www.cajomi.de/GeoControl/geocontrol_features.htm
http://www.viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm
http://michaelmak.es/photoshop-and-hgt-files/
http://www.georeference.org/doc/import_surface_srtm.htm
http://www.earthondrive.com/index.php?route=product/category&path=59
http://www.viewfinderpanoramas.org/dem3.html
http://www.osgvisual.org/projects/osgvisual/wiki/OsgTerrainData