I love that Chicago's CTA believes in a much more open development model: http://www.transitchicago.com/apps/ http://www.transitchicago.com/developers/default.aspx

More data:

https://www.metrochicagodata.org/ https://data.cityofchicago.org/

It's all a part of Chicago's OpenGov work and its incredible how much data and work is out there. Here's a list of apps that people made in a city-sponsored competition:

http://www.smartchicagocollaborative.org/list-of-apps-for-me...

And here's a link to one of the meetups that try to do something cool with all that open data from the City:

http://www.opencityapps.org/#about