As an example, say I have an Authors channel, and I have an Authors List channel. The Authors channel contains a lot of biographical info on my writers; the Authors List channel lets me create a listing of writers like maybe "Fall 2013 Best-Selling Authors." The Authors List channel is primarily populated by use of its Matrix field, which is where you're picking the authors to list.
What would be really nice is if there is some way when looking at any author in the Authors channel's back end to tell if that Author is currently included in a Matrix field in that Authors List channel. So that I can bring up Donna Tartt and see that she was listed in my Authors List entries of "Fall 2013 Best-Selling Authors," "Fall 2002 Best-Selling Authors," "Winter 1993 Best-Selling Authors," and "Fall 1992 Best-Selling Authors."
This would save a ton of time and be much less error-prone vs our Plan B, which is having to create a big text field in the Authors channel and go in and manually note by hand each time we include an author in an Authors List.
(oh, forgot, while I'm asking for the moon: what would be REALLY awesome is if this automagically generated listing of Authors List entries could include both its entry and its date. rough dates are sort of inherent in my example Authors List entry titles above, but not in my actual data. thanks!)