I do not use many Excel keyboard shortcuts. But my switch from Windows to Mac OSX showed that I really was dependent on a few that were hard to find in my new software. Maybe you have the same issue.

• In Windows, I constantly used the Office 2010 (Windows) CTRL-MINUS and CTRL-PLUS to add/remove columns and rows. For some reason CTRL-PLUS does not work in Office 2011. To insert a row or column on the Mac, select it and hit CMD-I instead.
• I use the soft line break in an Excel cell a lot, on the PC it is ALT-ENTER, on the Mac it is ALT-CMD-ENTER.