Web Map Servers (WMS)

demis.nl
All Earth (JPEG Image, 800x400 pixels)
All Earth - with country borders (JPEG Image, 1000x500 pixels)
microsoft terraserver
Microsoft TerraServer Map Server - Get Capabilities
USA MA Westford - topo (JPEG Image, 800x500 pixels)
USA MA Westford - image (JPEG Image, 800x500 pixels)
digital earth
wmt.cgi (PNG Image, 800x400 pixels)
others
Welcome to CubeWerx
OGCNetwork
GIDB OpenGIS WEB SERVICES
OnEarth, server of the Landsat 7, WMS Global Mosaic
Available WMS and WFS servers - Confluence