OK, before I tell you what I just discovered, I feel compelled to note that I have been using a Macintosh since 1985!
I was watching a video tutorial this morning and the guy copied a file on the desktop by pressing Command-C and then switched to another folder and pasted it in there by pressing Command-V. Did you all know you could do that? I sure didn't. Not sure if it's useful, but it definitely took me by surprise, even though it's completely logical and obvious.
Thought you should know too!