Drop the mouse.
(Side note: Microsoft Office 2007′s behavior of showing keyboard shortcuts is absolutely brilliant. Its one of those simple features that leaves me wondering why it hasn’t always existed.)
Coding Horror doesn’t mention when a mouse is more efficient, but the use cases are pretty obvious: spacial manipulation. Web browsing, photo editing, graphic design, many video games, and, in some cases, user interface layout usually require a mouse for good reasons.