"Microsoft Excel has no keyboard shortcut for “save as”. Probably because they are *only* on version 11."
That was one of the Twitters that I posted on Saturday. However, as Jason Morin pointed out in the comments, you can use the F12 key to open the Save As dialog box.
Why didn't the twitterer know that? Well, when you go to the Keyboard Shortcuts topic in Excel's Help, there's an incomplete list. It doesn't even show Ctl + S as a shortcut to Save, let alone tell us how to do a Save As.
To find a full list of Excel Keyboard shortcuts, you can download one of the following files or view the list on the web page.
Chip Pearson's site
View: Excel Keyboard Shortcuts list
Download: Excel Keyboard Shortcuts Excel file
Contextures site
View: Excel Keyboard Shortcuts list
Download: Excel Keyboard Shortcuts Excel file
Microsoft Excel Team Blog
Download: Excel Keyboard Shortcuts Excel file
In a blog post from Sept 2007, there's also a discussion of what keyboard shortcuts you'd like to see.