When you write applications, it is important to include both the CUA and the Windows/Apple keyboard shortcuts, and get the tab order of keyboard accessible user elements right.
Many modern applications seem to put less and less emphasis on the most efficient user input device: the keyboard.
You should: it makes your application much more pleasant to use.
I wrote about CUA before, but the Windows and Mac shortcuts are just as important.
A small table (please post a comment if you know additions):
The Wiert Corner - irregular stream of stuff 