I am a huge fan of any paradigm-changing technology and OnStar - the GM invented service which integrates a car's computer and a remote call center is certainly one of these achievements. The service does lots of different things like provide turn-by-turn navigation but perhaps the crowning achievement of the service is the ability to connect to the call center when the vehicle's sensors indicate there has been a collision.
A few days ago, a couple was forced into their car at gunpoint near Chicago and a thief forced them to drive to a Currency Exchange to cash a check. On the way to the Exchange the woman was able to hit the OnStar emergency button on the remote control which alerted the police.
Here is a video of the woman who hit the OnStar button being interviewed.