Andre Svetsuk and the City Form Lab have just announced the Urban Networks Analysis Toolbox v1.01 for ArcGIS. This can be downloaded free. The following text is from their web site.
As the first of its kind, this ArcGIS toolbox can be used to compute five types of graph analysis measures on spatial networks: Reach; Gravity; Betweenness; Closeness; and Straightness. Redundancy Tools that come with the software, additionally calculate the Redundancy Index, Redundant Paths, and the Wayfinding Index.
The tools incorporate three important features that make them particularly suited for spatial analysis on urban street networks. The tools are aimed at urban designers, architects, planners, geographers, and spatial analysts who are interested in studying the spatial configurations of cities, and their related social, economic, and environmental processes. The toolbox is built for easy scaling – it is equally suited for small-scale, detailed network analysis of dense urban areas as it is for sparser large-scale regional networks. The toolbox requires ArcGIS 10 software with an ArcGIS Network Analyst Extension.