user.rb

class User < ActiveRecord::Base
  
  # These are all boolean fields defined for this User model. 
  # As we add more email columns, and add them to this array,
  # the named_scope below keeps up.
  EMAIL_COLUMNS = [:email_new_market_alerts, :email_new_announcements, :email_stock_notices]
  
  named_scope :unsubscribed, lambda { { :conditions => EMAIL_COLUMNS.inject({}) { |conditions, column| conditions[column] = false; conditions } } }
end

# Find everyone who doesn't want any of our emails
User.unsubscribed