I would like to create movie lists where people can track what has already seen and what is still to see.
So, when one user sees my list, he should be able to push a button that says "Yes, I've seen it" and this information should be visibile only to him.
It could be great also to have a progress bar that says to the user...you've seen the 55% of the items in this list.
Of course this feature can be used for anything.
What do you think?