This week I worked on introducing an early version of state saving in JupyterLab for plugins that need to persist page refreshing. Some of it is in master already, some more of it is still being developed.
We can try to put you in contact with GitHub see if they can do some internal query of their notebooks. We can also give you access to Google Analytics on Nbviewer, don't know if that would be helpful to find notebooks.
There's a large, open PR on state management and application restoration on page refreshes that should be finished within a day or so. If you want to follow along, there's an overview of the restoration lifecycle in the PR description: jupyterlab/jupyterlab#1291
Demos at Gateways 2016, NYU, PlotCon and multiple other venues (fperez, jason). Very well received, lots of interest for potential collaborations. Special thanks to Matt Rocklin & Luke Canavan for great Dask demo.
Ongoing work on the embedding of widgets with formal json spec for widget state + sphinx extension. (Widget state can be fully generated from python backend now, which will enable pure-python sphinx extensions)