Every driver has been there. Driving along quite happily when they become aware of all the other drivers flashing. A quick check shows that the headlights should be on, but pulling over and it's discovered that the bulbs are blown.
"What can you do?" asked Mac Buck, editor of the hugely popular App World! magazine. "Who carries spare bulbs in their car? Well, apart from my dad. My dad's a special case, he can rebuild his car from the spares in the boot."
Instead, suggests Buck, download the app iSpareBulb.
"This is a fantastically simple app," said Buck. "It can become a break-light, a tail-light, a headlight, a fog-light (front or rear) or an indicator. It can, with a bit of tweaking in the settings, even become a vanity mirror light."
The iPhone is then duct-taped to the light housing that has failed.
"Headlights and tail-lights are relatively easy to duplicate," said Buck. "They're on all the time. Indicators and break lights are a different kettle of beeswax."
Although Le App, the French company behind the applelet, are reticent to explain how the app does it, Buck has worked out that the app uses the WiFi sensors to detect electrical surges that would otherwise turn on the indicator or break light.
"I turned off the WiFi," said Buck, "and it didn't work. With it turned on, it did. And it worked really well."
The bright Ultra-AMOLED Retina display is bright enough to replace a headlight, but it has it's downsides, according to Buck.
"Having the screen that bright eats through even a fully charged battery inside four hours," he said. "And who has a fully charged iPhone battery for longer than twenty minutes? However, it should be enough to serve in an emergency."
Where multiple bulbs have gone, multiple iPhones are required, which is also a downside for most people. Not for Buck.
"I put my iPad as one headlight, my iPad2 as the other headlight, my spare iPhone 1 and 2 as break lights, a couple of iPods as indicators and my iPhone as the interior light for when the doors are opened," said Buck. "It worked really well until stone chips took out the iPads. I'm a bit gutted at that."