Here's one incredibly practical application of Netflix's API: a Twitter account created to notify users when movies expire from Netflix Instant.
THE BODYGUARD (★★★) retires tomorrow: http://t.co/bXjwomn
The account, @queuenoodle, is based on a simple script that identifies about-to-expire movies. The automated feed alerts you to movies that will expire shortly, so if they're in your queue you can watch them before they're gone. Each tweet also includes the movie's star ranking, so you can know which movies you need to get on top of watching and which you can skip.
It's a quick, simple reminder to keep an eye on your Instant movie queue so you don't lose them. Also: Donnie Darko expires on Monday!