Some of the programs I use or used utilized task checkbox to show status and progress, I think doing this in Toodledo could help provide more info about task without taking up screen real estate - this could especially help when using TD on the phone.
Progress 25% or less - darken 1/4 of checkbox
Progress 25-50% - darken 1/2 of checkbox
Progress over 50% - darken 3/4 of checkbox
Status "Waiting" - show a sand clock icon instead of checkbox
Status "Delegated" - show a person icon instead of checkbox
(status icons take precedence over % completion)
This could probably be easily implemented without making major changes to the rest of the program.