In this post, I will store [updated] links to different sources of GIS data. This collection may vary according to my works, but it will mainly contain data about EU, UK and Spain.
UK
British Government’s data https://data.gov.uk/
Ordnance Survey Open Data https://www.ordnancesurvey.co.uk/
British Geological Survey. OpenGeoscience http://www.bgs.ac.uk
Scottish Spatial Data Infrastructure https://www.spatialdata.gov.scot
Scottish Natural Heritage https://gateway.snh.gov.uk/natural-spaces/
Edinburgh Council Open Data http://edinburghopendata.info/
Spain
Spanish Government Open Data http://datos.gob.es/es/catalogo
National Center for Geographic Information http://centrodedescargas.cnig.es/CentroDescargas/index.jsp
Junta de Castilla-La Mancha Open Data http://data-castillalamancha.opendata.arcgis.com/
EU
Eurostat GISCO. Administrative boundaries, infrastructure and land cover http://ec.europa.eu/eurostat/web/gisco
Global
UNESCO Institute for Statistics http://data.uis.unesco.org/
Global administrative areas http://www.gadm.org/
University of Pennsylvania international GIS database http://guides.library.upenn.edu/globalgis
USA
Federal government’s open data site https://www.data.gov/open-gov/
Enrique Valero 