Today’s invention is a GPS-equipped phone device which is linked to the airbags in one’s car.
In the event that a bag is deployed, a message detailing the location is automatically sent to a preselected list of contacts (including eg the ambulance service, police, next of kin, Twitter, etc).
It seems that something like this exists. Not sure if it pre-dates this post.
http://www.timesonline.co.uk/tol/news/uk/scotland/article7134020.ece
Enough of a bandwagon exists for MEPs to start jumping on it though.