Save As Cell Contents, instead of the default "Book1.xlsx"
Often I have typed a heading in a workbook, and then had to re-type the same or nearly the same information when saving the workbook. MS Word has an intelligent guess at the Save As option by using the first words in the document, but Excel just offers Book1.xlsx. What if we could have Save, Save As, and Save As Cell Contents? In other words, select your chosen cell, click on Save As Cell Contents, and you have your desired file name with no duplication of effort.
Kenneth Barber commented
Except that in Microsoft Word, the first words often aren't what you want to call your file. For example, my title within the document might be "Software Engineering Assignment 1", but I'll just call the file "Assignment 1" and keep it in my "Software Engineering" folder.
For Excel, you usually have multiple sheets, and so unless you have a summary sheet, your file name won't come from any cell. Also consider how often you have to Save As--not much. If that's not your case, you're probably doing some sort of daily files, in which case you'd be better off keeping all of your daily data in 1 file. Things are easier when everything is in 1 place.