Say that you have Word configured to insert quotation marks as curly rather than just normal typewriter-like straight marks (which correspond to the ASCII quotation characters). But say that at some point you need to enter a straight quotation mark, for instance when you're entering some HTML code. What to do?
I struggled with this for years, until I accidentally discovered a trivial solution: After you type the quotation mark and it gets automatically made curly, just hit control-Z (undo), and it'll straighten out. The same seems to be the case for all the Word auto-corrections, such as (c) becoming a copyright symbol (if you have that set) and the like; hitting control-Z returns the item to being exactly what you typed.
My apologies if this is old hat to all of you, but my guess was that many people don't know about this, just as I didn't until recently. I think this is so for Word 2003 as well as Word 2007.