uicontrol('Style','edit') and uitable cells should support a "PICTURE" input validation field; the field could be a string containing a % format, or a string containing a regex, or the handle of a routine. The validation would be "live", as characters are typed, with user notification (e.g. a beep, with provision made for visual notification for the deaf) as soon as they enter the wrong character.
drag-and-drop. Extended cut-and-paste (e.g., blocks of table)
Ability to find out which uitable cells are visible, and ability to set the scrollbars so that a particular part is visible.
Embedded 'vi' editor mode.