The Metropolitan Philadelphia Indicators Project released an online map, MetroPhilaMapper which allows to easily map over 300 indicators for the region, including land use patterns, population characteristics, school district spending and performance, income and wage data, and crime patterns.
A discussion about referencing and bringing historical maps into a GIS recently took place on the MapHist Mailing list. The thread on “Historical maps in GIS, accuracy, RMS error” starts here . It ranges from evaluations of different transformation algorithms to the question of why would we want to georeference historical maps at all and [...]
There are now two sites that offer download of from OpenStreet in varying formats, including shapefiles and GPS: CloudMade and Geofabrik (for Europe).