Working on Spacial data.
Free GIS data sources
Well the government of different countries provide free access to spatial data.
Government like US, England, Korea, New York, Chicago etc.. provides access to the different types of spacial data.
Well few are mentioned below from where one can access spatial data
1. Esri Open data hub
2. Natural earth data
3. USGS Earth explorer
4. OSM - Open Street Map
5. NASA (SEDAC)
6. Open Topology (famous for providing LIDAR data)
7. UNEP
8. NEO
9. Sentinal Satellite data (Copernicus)
10. Terra Populus