Sooner or later someone who watches too many movies and has a numeric keypad, an Arduino board, and a technical-looking briefcase is going to make a movie prop that resembles an explosive device. However it's fun, could have other applications - for example a time-delay door lock, or more fun. It's up to your imagination. However - be responsible. Here's a video of the example prop:
For more information, including the hardware design and Arduino sketches - visit theinstructable here. And we're on twitter and Google+, so follow us for news and product updates as well.
When building your own Arduino-embedded projects, consider our Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound and knock detection: