Set-up a OpenTripPlanner instance loaded with the data for Zurich and let people visualize how far they can travel within a given timeframe by public transport and on foot. Visualization would be done with the analyst part of OpenTripPlanner as outlined in http://opentripplanner.com/2012/07/visualizing-urban-accessibility-with-opentripplanner-analyst/

• GTFS data for Zurich, most probably by scraping zvv.ch or
• OpenStreetMap
• A dataset from Zurichs OGD portal to show the reachability

• packi
• and other team members

• OpenTripPlanner
• https://github.com/openplans/OpenTripPlanner/wiki