This style highlights untagged and unconnected nodes in a way
{{{
#!style type="mapcss"
meta {
  title: "Highway Nodes";
  version: "1.1_2014-01-16";
  description: "Highlights untagged and unconnected nodes in a way";
  author: "naoliv";
  link: "http://josm.openstreetmap.de/wiki/Styles/Highway_Nodes";
  watch-modified: true;
}

/* highlight all the nodes */
way[highway] > node {
  symbol-size:10;
  symbol-shape: square;
  symbol-stroke-color: #00ffff;
  symbol-fill-color: blue;
}

/* dim the nodes that we don't want */
node:connection, node:tagged {
  symbol-size:4;
  symbol-fill-color: #808080;
  symbol-stroke-color: #808080;
}
}}}