name

tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'XlSheetType')
variables = tobj.variables
variables.each do |variable|
  puts "#{variable.name}"
end

The result of above script is following:
  xlChart
  xlDialogSheet
  xlExcel4IntlMacroSheet
  xlExcel4MacroSheet
  xlWorksheet