Google Maps

• Plot multiple locations
• GMapCreator to create web pages with embedded, customized Google Map

Street Maps

• OpenStreetMap
• OpenStreetMap Help & Wiki

Topographic Maps

• The National Map Seamless Server (USGS) ◊ National Map Viewer
• USGS Topographical Quadrangles ◊ Select and Download ◊ Search by State

Other Maps

• National Atlas ◊ Data Download ◊ Printable Maps (States/Counties)
• City of Fort Wayne - GIS
• Allen County (IN) - GIS
• The IndianaMap Project and The IndianaMap Viewer — view and query more than 220 layers of GIS data, including aerial photographs, land cover, reference layers, and layers related to infrastructure, demography, environment, hydrology, and geology.
• Indiana County Map and historical census data (for genealogical purposes); easily get county maps and historical census data for any state.
• Color Landform Atlas of the United States
• WikiMapia

Google Earth

• Official User's Guide
• Google LatLong Blog
• Google Earth Hacks
• Google Earth Tips Archives
• Google 3D Warehouse
• Google Geo Developers Blog
• KML -- Google Code
• KML Reference
• libkml -- C++ API
• Google Maps API
• GPlotter (JavaScript)
• NorthGates KML Editor
• Timelapse Landsat Images

NASA's World Wind

• SourceForge Project Site
• World Wind Java SDK
• World Wind (SDK) Applications & Applets

KDE Marble

• How to become a Marble developer
• Fun with free maps on the free desktop (LWM.net article)

Historical Maps

• David Rumsey Historical Map Collection
• Free Maps The Map Store of Minnesota
• 1930 Plat Books for Missouri Counties

Maps and GIS Data

• Libre Map Project — The purpose of the Libre Map Project is to aggregate and make digital maps and related GIS data available for Free.

• The US Geological Survey
• USGS Publications Warehouse

• A Gallery of Map Projections
• Legendary Map Makers of the World

Map Collecting

• Road Map Collectors Association

Map Stores

• Maps of the World
• USGS Publications Warehouse

• Mapping Hacks (blog)

Choropleth Maps

• Wikipedia article

Excel

• Conditional Colors of Shapes
• Series of articles on Clearly and Simply
  • Choropleth Maps with Excel
  • Multicolored Choropleth Maps with Excel
  • A Map Template for Brazil Including an Alternative Approach
  • Choropleth Map Template USA by Counties
  • Build your own Choropleth Maps with Excel (importing SVG maps into Excel)
  • Spice up your Choropleth Maps with Excel

Other

• How to Make a US County Thematic Map Using Free Tools

Other Considerations

• Color Advice for Cartography — "a diagnostic tool for evaluating the robustness of individual color schemes"

Cartographic / Geographic Open Source Software

• GEOTRANS
• GeographicLib (C++)

Cartographic / Geographic Algorithms

• Geodesic Distance - Vincenty Formula
• Calculate Distance and Bearing
• Havesine Formula (Wikipedia)

GPS Software

• GPS Utility
• GPS Freeware (links)

Commercial Mapping / GIS Software

• ESRI — ArcGIS