My home computer's mouse practically died several days ago. And while I am quite busy to go out and buy a new one, I still have to use my home PC, so my only choice is to use the keyboard.
It was not until now when I felt what a great job Microsoft did to enable keyboard support. While I still feel somewhat awkward without the mouse, I nevertheless can access all the features I need in Windows, Outlook and Word. However, certain 3rd party applications and Web sites are a different story - they imply that all their users utilize a pointing device. Not always the case, you know :)
Moral: If you are working on a client application, make sure the mouse and the keyboard users are equal. Go even as far as putting away your mouse and trying to use your application only with the keyboard. Believe me, your karma will be wa-a-y cleaner! ;)