Tutorial on --ns* options in mongorestore

The new options in mongorestore to deal with database and collection names as namespaces seem to be very powerful. While the doc page contains some examples, a tutorial on how to achieve certain goals might be beneficial. Some suggestions:

• Copy a database under a different name with mongodump ... | mongorestore ...
• Exclude collections with 'test' in the name
• Include collections only when they have 'production' in the name