I try to measure how well a node is connected to the rest of the network. If a city has a distant suburb connected with one sole road, it's connectedness is, say 1. If it's connected by 2 roads, it's 2, and so on. A point in the middle of the city is connected infinitely.

What are plugins or algorithms available?

I personally prefer open source solutions (QGIS, PostGIS, or python-based), but other options are also welcome.