Some of the many, many videos and DVDs we've accumulated over the years.
I have to wonder how much longer we'll even have "hardcopies" of movies. I already really like to just pick something to watch on Netflix's Instant Watch instead of waiting for a DVD to come in the mail. Not everything is available, though, so if I want to see something relatively current or popular, I have to wait for a DVD.
But how long will it be before you just pay another $.50 or $1.00 and you get to see "premium" movies. Very soon, I'm sure.