Alasdair Rae of the University of Sheffield has drawn together a really useful collection of data for planning based research. Have a look - http://ajrae.staff.shef.ac.uk/#resources
Natural Earth - From the website:
Natural Earth is a public domain map dataset available. Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.http://www.naturalearthdata.com/
ETOPO1 - From the website "ETOPO1 is a 1 arc-minute global relief model of Earth's surface that integrates land topography and ocean bathymetry. It was built from numerous global and regional data sets, and is available in "Ice Surface" (top of Antarctic and Greenland ice sheets) and "Bedrock" (base of the ice sheets) versions." http://www.ngdc.noaa.gov/mgg/global/global.html
D maps - free world, continent and country outline maps http://d-maps.com/
n.b. Do not click on DOWNLOAD _ right click on map - 'save target as'
Global landcover http://glcf.umd.edu/
Oceans Maps - bathymetry
History of Cartography
The History of Cartography Project http://www.geography.wisc.edu/histcart/ is an immense six-volume international research, editorial and publishing venture spanning mapping from pre-history to the present.
Recent donations have funded free online delivery of Vols 1-3 http://www.press.uchicago.edu/books/HOC/index.html