PostGIS Online is a project started by Nicklas Avén.
This site will allow you to dynamically try PostGIS SQL statements on line without even installing PostGIS. You can try some of the examples in chapter 2 of our book that are self standing examples and watch these dynamically displayed on a map.
For example type in an SQL statement such as:
SELECT ST_GeomFromText('POLYGON((-0.25 -1.25,-0.25 1.25,2.5 1.25,2.5 -1.25,-0.25 -1.25), (2.25 0,1.25 1,1.25 -1,2.25 0), (1 -1,1 1,0 0,1 -1))') As the_geom
Then click the Map 1 button and watch as the geometry is drawn on the screen.
pgRouting: A Practical Guide is available in Hardcopy from Hardcopy from Amazon. E-Book or Bulk discounts on Hard-copy from Locate Press.