A custom Cucumber Report Formatter to list all tags, how many of each there are, and sort them by that count.

reports.rb

module Report
 class Tags
    def initialize(step_mother, path_or_io, options)
      @all_tags = []
    end

    def tag_name(tag_name)
      @all_tags << tag_name
    end

    def after_features(features)
      tracker = Hash.new(0)
      @all_tags.each { |tag| tracker[tag] += 1 }
      sorted_tracker = tracker.sort_by {|tag, count| count }
      sorted_tracker.each {|tag_count| puts "#{tag_count[1]}: #{tag_count[0]}"}
      puts "#{@all_tags.count} Tags in total"
    end
  end
end

Toss this into your features/support directory, and then run it with cucumber -d -f Report::Tags