In ArcMap Table of Contents, allow users to change the checkbox to a radio button. Only allow one of the radio buttons to be on at any one time (when hit, toggle others off). This would be useful to layers being totally overlaid and not visible (example: 2 imagery datasets), where only one can be seen (highest in TOC covers those that are lower).
Bonus: the possibility of a radio button set within a group, though this may conflict with the above for individual user desired behavior.
Nice side impact is improved drawing speed, as layers covered up are not rendered.
