Jeff Atwood recently posted a list of windows tips and tricks on his blog.  The list included using Ctrl+C to copy the text out of message boxes.  This trick has been invaluable to me for a while, especially in place of "can you send me a screen shot of that?" 

But here's the kicker: Who knew that you could Ctrl-Click the taskbar to select multiple items and then perform actions (e.g. cascade,tile,close) on your selection?  Where have I been?  Jeff, you're the man.