class Fixnum
  def seconds
    self
  end

  def minutes
    self * 60
  end

  def hours
    minutes * 60
  end

  def days
    hours * 24
  end

  def ago
    Time.now - self
  end

  def from_now
    Time.now + self
  end
end

puts Time.now        # => Thu Dec 23 09:41:04 +0100 2010
puts 3.days.from_now # => Sun Dec 26 09:41:06 +0100 2010