MS Excel is a fantastic spreadsheet program, but it doesn't make a very good word processor. Unfortunately, this fact doesn't appear to be very widely known, and many documents written with Excel are sent out for translation.
But don't worry: Felix has you covered here as well. Just as with MS Word and MS PowerPoint, Felix has an interface that works right from MS Excel. So whether you're translating a spreadsheet with the month's sales figures or the next great American novel written as an Excel file, Felix makes your job as easy as possible.
You can also register glossaries and word lists in Excel format as Felix glossaries. Simply create a list with two columns – source terms on the left and translated terms on the right – then select the top source term in the list, and select "Add Glossary" from the Felix menu.