Geographical information systems. Everything geospatial, including geographical data processing, visualisation, data collection, spatial databases and just maps.
Somewhat intersecting with tags such as databases, visualization, design, but still GIS is interesting as separate topic. There’s even GIS day.
Examples of posts:
“Geospatial” or “geo” might be less-cryptic tags but I agree with the recommendation!
Geospatial would be the better of those two options, I think