It's things like this that re-affirm my faith in the world of gadgets. No longer do I need to plug an air compressor into a car cigarette lighter socket. If you think about the number of things which can be powered from this, such as sat nav's, iPods, portable coolers, compressors etc it seems like a bargain.
Note the 5A limit. If you try to power something with a higher current drain, the circuit breaker will cut the power.