It's hard to beat that setup for generating tension. Thanks to Nootropic Design it's one you can recreate thanks to their Defusable Clock kit.
The Defusable Clock is a fully-functional alarm clock just like you’d expect (a normal beeping alarm, snooze alarm, etc.). But at any time you can press the big red button to start a scary countdown sequence exactly like bombs in Hollywood movies. There are 4 wires across the top of the clock. You have 10 seconds to choose the correct wire to cut: one wire stops the countdown and saves the day, two have no effect, and one will “detonate” the device immediately. These role of each wire is randomly assigned when the detonate button is pressed, so it’s a new challenge every time.
Check out their gallery of completed projects to see dozens of very cool devices made from their electronics. It's packed with prop porn of the most glorious sort, from simple dynamite bombs to incredibly sophisticated terrorist bioweapons.
It should go without saying that this particular type of prop comes with a "Don't be an idiot" disclaimer.