[Discover] Length Of A Degree Of Latitude And Longitude Calculator http://www.csgnetwork.com/degreelenllavcalc.html
(conversion distance longitude latitude) 
[Discover] Mapnik - OpenStreetMap http://wiki.openstreetmap.org/index.php/Mapnik (maps gis openstreetmap osm)
[Discover] Google Static Maps API - Google Code http://code.google.com/apis/maps/documentation/staticmaps/ (google static map geo)
[Discover] Deploying your own Slippy Map - OpenStreetMap http://wiki.openstreetmap.org/index.php/Deploying_your_own_Slippy_Map (mapping maps openstreetmap api)
[Discover] Cylindrical Equal Area http://www.remotesensing.org/geotiff/proj_list/cylindrical_equal_area.html (reference gis postgis)
[Discover] Orbit Geospatial Technologies http://www.orbitgis.com/ (java software gis)
[Discover] PerryGeo http://www.perrygeo.net/wordpress/ (maps blog opensource programming)
[Discover] Mapnik - OpenStreetMap http://wiki.openstreetmap.org/index.php/Mapnik (maps gis openstreetmap osm)
[Discover] Google Static Maps API - Google Code http://code.google.com/apis/maps/documentation/staticmaps/ (google static map geo)
[Discover] Deploying your own Slippy Map - OpenStreetMap http://wiki.openstreetmap.org/index.php/Deploying_your_own_Slippy_Map (mapping maps openstreetmap api)
[Discover] Cylindrical Equal Area http://www.remotesensing.org/geotiff/proj_list/cylindrical_equal_area.html (reference gis postgis)
[Discover] Orbit Geospatial Technologies http://www.orbitgis.com/ (java software gis)
[Discover] PerryGeo http://www.perrygeo.net/wordpress/ (maps blog opensource programming)