It's pretty well known that the best way to eat an elephant is one piece at a time.
It would be amazing if it was possible break down the tasks in the todo lists into smaller subtasks that can be then ticked off one by one. To me, checking off small goalposts on the way is massively motivating. It's a visual representation of progress that helps to keep going.
[indent]Clean living room
I think it would be very intuitive if I could just drag task B into/onto task A, which would then make task B a subtask for task A. You could use indentation in front of the subtasks to make it clear that it's a subtask, not to be confused with the main task.
Otherwise, great product! Could become the first chrome extension I'm willing to pay for.