Array#columnize.rb

class Array
  # Handy when outputing a list in two columns, such as:
  # 
  #   A   B       A   C       A   C       A   D
  #               B           B   D       B   E
  #                                       C    
  #
  def columnize
    if size <= 1
      [ self, [] ]
    elsif size % 2 == 0
      [self[0...size/2], self[size/2..-1]]
    else
      [self[0..size/2], self[size/2+1..-1]]
    end
  end
end