Web Mapping Libraries:

Combination Web Map Libraries:

http://openlayers.org/ol3-cesium/ OpenLayers3 + Cesium
http://terria.io/ Leaflet + Cesium

Basemaps:

USGS Scanned Topo

http://services.arcgisonline.com/arcgis/rest/services/USA_Topo_Maps/MapServer/tile/{z}/{y}/{x}

Mapbox Satellite

http://{s}.tiles.mapbox.com/v3/energy.i04dnk87/{z}/{x}/{y}.png

OSM Humanitarian

http://{s}.tile.openstreetmap.fr/hot/{z}/{x}/{y}.png

The National Map - Imagery Topo

http://basemap.nationalmap.gov/arcgis/rest/services/USGSImageryTopo/MapServer/tile/{z}/{y}/{x}

Mapbox Terrian

http://{s}.tiles.mapbox.com/v3/energy.map-ayrdk7iy/{z}/{x}/{y}.png

Stamen Terrain

http://{s}.tile.stamen.com/terrain/{z}/{x}/{y}.png

Stamen Toner

http://{s}.tile.stamen.com/toner/{z}/{x}/{y}.png

OpenStreetMap

http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png

MapBox Topography

http://{s}.tiles.mapbox.com/v3/energy.map-ayrdk7iy/{z}/{x}/{y}.png

Energy Transmission

http://t2.beta.itoworld.com/183/6b4d21186086ce1b16e5e03f56fc7249/{z}/{x}/{y}.png

Open Map Surfer Boundaries

http://openmapsurfer.uni-hd.de/tiles/adminb/x={x}&y={y}&z={z}

Hike Bike

http://{s}.tiles.wmflabs.org/hikebike/{z}/{x}/{y}.png

CartoDB Dark Matter

http://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png

ESRI World Imagery

http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}

OpenCycle Map

http://{s}.tile.thunderforest.com/cycle/{z}/{x}/{y}.png

The National Map - Hydrology

http://basemap.nationalmap.gov/arcgis/rest/services/USGSHydroNHD/MapServer/tile/{z}/{y}/{x}

The National Map - Imagery

http://basemap.nationalmap.gov/arcgis/rest/services/USGSImageryOnly/MapServer/tile/{z}/{y}/{x}

The National Map - Topo

http://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer/tile/{z}/{y}/{x}

Thunderforest Transportation Dark

http://{s}.tile.thunderforest.com/transport-dark/{z}/{x}/{y}.png

Basemap Services:

JJediny/Geo.md