Admittedly, this has happened to me before. And let's not lie here, it's happened to you too. Let's face it, sometimes we do forget to zip up.

Randy Sarafan, the Technology Editor at Instructables, has a useful tutorial to combat this. By using conductive thread, a small circuit board and a vibrating motor, he's created a near invisible device you can make sure you've zipped up.

As to actually needing a device like this all the time, you probably have more serious problems than just forgetting the fly.

[YouTube via The Red Ferret Journal]