I think it would be super useful to be able to mark a to-do list note as "done" by strikethrough-ing the note's name in the list of notes. This would allow users to see at a glance if a note with a lot of to-do items in it had anything left undone.
This could be done by finding all the to-do items in the note and seeing if any are left incomplete. I would also propose that if it contained too much non-to-do text the name wouldn't be struck through (ignoring titles, tables(?), headers and lists for this check). Maybe this would be disabled manually instead?
I don't think this would be very complicated to implement and could probably be done with just a plugin but I think the exact spec being nailed down is the problem.