I tried not to create this page, but I couldn't resist. I hope you can't resist these blogs, either!
GIS Education Community hosted by ESRI (focussing on ArcGIS, ArcGISOnline, and general GIS topics)
Bing Maps blog hosted by Microsoft
Free and Open Source GIS Ramblings working with free and open source geographic information systems
Paul Shapley's Open Source GIS blog
Strange Maps cartographic curiosities from Frank Jacobs
The Map Room (map entries now continue at Jonathan Crowe)
The BIG Map Blog interesting maps, historical maps, BIG maps
Geographicus Antique Map Blog antique maps and the rare map trade
Spatial.ly visualization, spatial analysis, neat maps
Borderlines Frank Jacobs moonlighting in the NY Times, exploring the stranger international borders
Diana Maps from Diana Sinton, Director of Spatial Curriculum and Research at the University of Redlands
The GIS Doctor geospatial analysis, interesting online mapping applications, GIS software ...
Spatially Adjusted from the creator of Planet Geospatial
AnyGeo anything geospatial from a GIS user for GISusers
Mapperz UK-focused, but general news on maps and services