An improvement upon the previous example. A Natural Earth dataset is transformed into topoJSON while keeping the original properties. This lets it possible to display labels even for the countries that have no ISO code (stylized in italics in the map).
These are the commands used to prepare the data:
wget http://naciscdn.org/naturalearth/50m/cultural/ne_50m_admin_0_countries.zip
unzip ne_50m_admin_0_countries.zip
ogr2ogr -f GeoJSON ne_50m_admin_0_countries.geo.json ne_50m_admin_0_countries.shp
geo2topo -q 1e5 countries=ne_50m_admin_0_countries.geo.json > ne_50m_admin_0_countries.topo.jsonLabel placement is far from ideal. The centroid is not suitable in some cases (e.g., France). There is also a substantial overlap.