MongoDB: most popular email domains

gistfile1.js

var emails = {};
db.users.find().sort({_id: -1}).forEach(function(d) { 
    var email = d.email.split('@')[1];
    emails[email] |= 0;
    emails[email]++;
});

var sortable = [];
for (var email in emails)
      sortable.push([email, emails[email]])
sortable.sort(function(a, b) {return b[1] - a[1]})

printjson(sortable);