How do you get the miniature date navigator calendars in the navigator pane window to stack one on top of the other? Or get two or more in a row?

If you drag the interior border (right edge in Outlook 2003's navigation pane, left edge if using the Taskpad in any version) the width of a navigation calendar, you'll get more calendars in each row. To get them stacked in a column, you need to make more vertical space. If using the Taskpad, drag the border separating tasks from the calendar down one or more calendar heights.

When the calendar is on the left, in the navigation pane, you need to free up vertical space. You can do this by increasing the Outlook window size (using the maximize button or raise the screen resolution) or by removing the Calendar views from the navigation pane (View, Navigation pane, Show Views in Navigation pane) or removing calendars from the list.