The ability to automatically have certain toolbars turned on or off depending on a folder's view settings. For example, using the "Images" content type format, I could have a toolbar with frequently used image-related buttons automatically turn itself on when the "Image" content type was invoked, and turn itself off when I switch to, say, a music folder, with different view settings.
One potential problem, of course, is when there are two folders open, such as a source lister with image files and a destination lister with music files, but.......
Yep - and it fits in with the recent topics on the forums asking if there was any way to associate toolbar configurations (on/off/placement) with other 'appearance' items like Layouts, Folder Formats, etc...
For your question about how to handle dual-display listers with such logic... there have also recently been some requests to have certain toolbar components associated with specific sides of dual-display listers... i.e. mostly having to do with separate 'pathbars' for each file display. Perhaps we could have file-display associated toolbars?