Meterology Weather Station (Courtesy Pixabay)
General Mapping:
DistrictBuilder (free and open source redistricting tool)
Felt (open-source / currently free)
Leaflet (open-source JavaScript library for mobile-friendly interactive maps)
Natural Earth (Free vector and raster map data at 1:10m, 1:50m, and 1:110m scales)
Open Street Map (Free)
OpenTopography (Community access to high-resolution, Earth science-oriented, topography data, and related tools and resources)
QGIS (Free & Open Source Geographic Information System)
storiiies (Free Online Storytelling Platform)
Cave Mapping Sites:
CaveWhere (Enables building and visualizing underground cave maps)
Compass (Designed to edit, process, analyze and view cave survey data using any Windows-based computer)
Therion (Processes survey data and generates maps or 3D models of caves)
Tools:
ColorBrewer (Color Advice for Maps)
Contrast Checker (Test color contrast compliance with the Web Content Accessibility Guidelines (WCAG) as set forth by the World Wide Web Consortium (W3C).)
MapAnalyst (A free and open-source software application for the accuracy analysis of old maps. Its main purpose is to compute distortion grids and other types of visualizations that illustrate the geometrical accuracy and distortion of old maps.)