I am starting to use theme switching to make the site more accessible to mobile devices.
It would be helpful to allow a different form configuration based on theme.
For instance, there are several modules which will switch to a special mobile theme when a site is accessed by a mobile device. If one of those themes is activated, it would be helpful to switch from a two column form to a one column form.
This is my simple thought, there may be better solutions or solutions people are already using.