I think many of us use MS Word and if you use it often then it is worth looking at the keyboard shortcuts available regularly to see which would be of help for the tasks you frequently. The full lists are available online, for Word2010 (including a quick reference card) and for earlier versions
These are a few of the lesser known ones which I find really helpful.
SHIFT+F5 goes back to the last edit you made in the document. Importantly this works even when you have closed the document, so I find it really helpful when working on a document over several weeks (such as when indexing it), for keeping track of where I am. It actually stores the last three changes made and cycles around them. Unfortunately it loses track of them when you save the document, so I select a word and press ctrl-B twice to bold, then unbold, it, just before closing it. That way, when I open the document next time, Shift-F5 takes me straight back to where I was last working.
When pasting text into Word (or trying to sort out someone else’s formatting):
CTRL+SPACEBAR removes all manual character formatting that is applied to the selected text and sets it back to the underlying paragraph style; and CTRL+SHIFT+N will apply Normal style
Still on formatting, we all know that CTRL+C and CTRL+V will copy and paste text, but CTRL+SHIFT+C and CTRL_SHIFT+V will copy and paste the formatting from one piece of text to another
When selecting text from a Word document to include in an index entry, whether by embedding or otherwise, it can be useful to change the case. Pressing SHIFT+F3 will cycle the selected text to all-upper-case, then all-lower-case, then Title-case. This is particularly helpful when selecting chapter or section headings and avoids having to retype the heading.
We should all know that pressing the Pilcrow button switches Show/Hide of hidden characters on and off, but, on Word2007/2010 in particular where it can be difficult to find, it is faster to use CTRL+SHIFT+8
One which, as indexers, we should all know – to insert an en-dash, press CTRL+NUMERIC KEYPAD MINUS SIGN