NASA visible Earth: http://visibleearth.nasa.gov/
Remote sensing data
Sea Surface Temperature: http://podaac.jpl.nasa.gov/sst/
Ocean topography (Sea Surface Height): Topex/Poseidon
http://podaac.jpl.nasa.gov/toppos/
http://podaac.jpl.nasa.gov/tpssa/
Precipitation: http://www.cpc.ncep.noaa.gov/products/global_precip/html/
ENSO and SOI:
http://www.cpc.noaa.gov/data/indices/index.html
International geographical data
GIS data from the United Nations: http://www.grid.unep.ch/data/index.php
Information on nomenclature of territorial units for statistics - NUTS: http://europa.eu.int/comm/eurostat/ramon/nuts/home_regions_en.html
Chesapeake Bay: http://www.cbos.org/
Secretaría de
Salud (SSA): http://www.ssa.gob.mx
El Instituto Nacional de Estadística, Geografía e Informatica (INEGI): http://www.inegi.gob.mx/
Agricultural data: http://www.defra.gov.uk
National statistics and UK demographic data: http://www.statistics.gov.uk/
http://www.statistics.gov.uk/census2001/
http://www.statistics.gov.uk/geography/maps.asp
Ordnance survey and UK maps: http://www.ordsvy.gov.uk/