"Google Earth for Philadelphia" with open source and open transit data.
Live demo: http://www.openphillyglobe.org/
Real-Time SEPTA locations and average weekday pedestrian activity at Philadelphia street corners in August 2013.
There is a great open-data movement in Philadelphia, but there is not a one-stop viewer for the heterogeneous datasets. OpenPhillyGlobe is an open-source web-based 3D globe for visualizing Philly's open data with an initial focus on simultaneously visualizing multiple transit layers.
OpenPhillyGlobe uses the Apache 2.0 license. It is free for commercial and non-commercial use.
We now have http://www.openphillyglobe.org/ for our project. Check it out in a browser that supports WebGL.