geojson.io - Create quick and dirty maps with points, lines and polygons.

Raster.io - GDAL (read raster) for Python

Terraformer.io - Allow spatial queries in the browser.

Mapsheet.js - Create quick maps using Google Spreadsheet.

MapIt is a service that maps UK postcodes and geographical points to administrative areas. It’s useful for anyone who has a postcode or co-ordinates of a point in the UK, and needs to find out what region, constituency, or council it lies within. It’s also great for looking up the shapes of all those boundaries.

Field Papers Make Digital maps with a Pen and Paper

MapKnitter is a free and open source tool for combining and positioning images (often from MapMill.org) in geographic space into a composite image map.

TileMill is a tool for cartographers to quickly and easily design maps for the web using custom data. It is built on the powerful open-source map rendering library Mapnik - the same

Jeo WordPress Theme acts as a geojournalism platform which allows news organizations, bloggers and NGOs to publish news stories as layers of information on digital maps.

Geojournalism Handbook