## preferred_contact.rb

module ContactMethods
  def self.included(base)
    base.class_eval do

      has_many :email_addresses,
        :extend => ContactFinders,
        :dependent => :destroy

      has_many :phone_numbers,
        :conditions => {:is_fax => false},
        :extend => ContactFinders

      has_many :fax_numbers,
        :conditions => {:is_fax => true},
        :class_name => 'PhoneNumber',
        :extend => ContactFinders

      has_many :mailing_addresses,
        :as => :addressable,
        :extend => ContactFinders


      has_many :im_accounts,
        :as => :imable,
        :extend => ContactFinders

    end
  end
end

## contact_finders.rb
module ContactFinders
  def preferred
    find(:first, :conditions => {:preferred => true})
  end
end

## user.rb
class User < ActiveRecord::Base
has_many :email_addresses,
        :extend => ContactFinders,
        :dependent => :destroy
end