When entering a date into a field using the popup calendar, it would be really handy to be able to navigate the calendar using the cursor keys. Some other systems I use have this ability, and it makes calendar navigation a breeze. Cursor up or down, and it moves one week earlier or later. Cursor left or right moves forward or backward one day at a time. I frequently find myself shifting dates around in small increments (mainly in my task management base), and it would be so handy to just hit Enter in a date field to bring up the calendar, tap a few cursor keys to change the date, then Enter again to save the change. The less I have to move between the mouse and keyboard, the better.