Slowly supplanting IBM's Lotus 1-2-3 in the nineties, Microsoft Excel has become the de-facto spreadsheet application for the business world, and learning it will add a nice touch to your resume, regardless of the clerical positions for which you apply. Excel 2010 is the current version, with Excel 2013 just around the corner (early 2013). Here's the new Backstage view:
New in Excel 2010: improved Ribbon and Backstage view, introduction of sparklines and slicers, and lots of behind the scenes improvements in performance and functionality.
The Excel web app was completely redesigned in the second half of 2012, and uses the Windows 8 "Modern" interface (formerly "Metro") - on the go, you can switch between editing spreadsheets in Excel 2010 or on the web, from a browser. Here's Excel web app running in IE:
Excel 2010 was a "minor upgrade", so nearly all these tutorials also apply to Excel 2007! This also means that you'll be up-and-running in no time if you're coming from the previous version.
Here's the full listing of tutorials: read through it for a great overview, or refresh your memory. For in-depth info, just click on the corresponding link!
Selection tips to quickly select cells, rows, columns, and worksheets in Excel 2010 / 2007 / 2003.