Compare Excel Sheets
http://www.moongift.jp/2009/09/compare_excel_sheets/
http://www.ghacks.net.zurukko.jp/2009/09/15/compare-excel-sheets/
Excel Compare 8.0
http://www.gold-software.com/download4584.html
Diff Doc
http://www.marroncraft.com/diffdoc/faq-tech.htm
めも、未検証