Dictionary of Abbreviations and Acronyms in Geographic Information Systems, Cartography, and Remote Sensing (Regents of the University of California) http://www.lib.berkeley.edu/EART/abbrev.html
Gallery of Map Projections: http://www.galleryofmapprojections.com/ (Paul B. Anderson)
Includes maps showing different types of map projections. Also includes publications and presentations by map professionals.
GeoCoder.ca: http://geocoder.ca/
"Geocode any North American location."
How to convert decimal degrees into degrees, minutes, seconds (Matt Rosenberg) http://geography.about.com/c/ht/00/07/How_Convert_Decimal_Degrees0962932697.htm
How to Measure Distances on a Map http://geography.about.com/od/understandmaps/ht/htscale1.htm (Matt Rosenberg)
Isolines: http://geography.about.com/library/misc/blisoline.htm (About.com: geography)
Journal of Spatial Science http://www.mappingsciences.org.au/journal.htm (Mapping Sciences Institute, Australia)
Map History: The History of Cartography http://www.maphistory.info/ (WWW-Virtual Library History)
This site covers journals and newsletters related to the history of cartography.
Mathematical Data for Bibliographic Descriptions of Cartographic Material and Spatial Data :
http://www.kb.nl/skd/mathemat.html (by Jan Smits)
Includes a section on "Petermann's bar scale values" that lists ways of measuring distance by country and gives the metric equivalent.
Mathematics of Cartography: http://math.rice.edu/~lanius/pres/map/ (Cynthia Lanius)
Relief Shading: http://www.reliefshading.com/
Provides information about shaded relief in mapping.
Shaded Relief: http://www.shadedrelief.com/ (Tom Patterson, U.S. National Park Service) Examples, articles and tutorials of shaded relief mapping.
Topographic Map Symbols: http://egsc.usgs.gov/isb/pubs/booklets/symbols/ (U.S. Geological Survey)
Assists in understanding topographic maps.