Buzzfeed : model derived from the very good article, a blog series on how to use MongoDB, Mongoose Object Data Mapping (ODM) with Express.js and Node.js. The article describes the steps required to build an RSS Aggregator application, similar to Google Reader.
GeoSpatial: introduction to MongoDB Geospatial feature derived from this blog post
GeoJSON: a Hackolade model with the different geometry structures of GeoJSON to be used as an external reference definition.
Kansas City Fountains: this model is drawn from an exercise in Steve Hoberman's class on 'Advanced modeling for NoSQL'. It is asked to model donations where the donor can either be an individual or a corporation, each requiring different fields. An good introduction to the concept of polymorphism.
https://hackolade.com/samplemodels.html