In Mexico City there is a bicycle loan system, EcoBici, and A few months ago I do a study about them about which stations are the most popular and which routes (travel from station to station) are more used, you can consult the study here (But only available in Spanish but add a nice map made with leaflet).

When the study was carried out, a graph was needed to explore the flows between the stations. The shiny app is documented as follows:

• The second tab shows a display of stations of a bicycle loan service in Mexico City, each node represents a station in the city.
• The edges represent very popular travel routes, on the left side you can choose the threshold from which routes are drawn in which $ n > 50$ travels arrive and you can also draw the routes in which they leave more than $ m > 50 $ trips per service station.
• The service API also provides information about the inflow of the stations, that information is what determines in node size.
• Finally an option to draw different colors of the nodes is given at the user's choice.
• Also on the graph you can zoom to see it better.

Today for the graph made with ggvis I have not found a way to share the image so that the functionality of displaying information by putting the mouse over the points is maintained, I have only managed to share the image as .png, however when using plotly the development time was much, much, less a web service is not required and I was able to share the graph keeping the said functionality in a .html file :D