that activates the fuel pump or any other critical engine run sub-system like injectors, etc. In order for the car to start - relay has to be activated (hidden switch or remote), once activated it latches and then resets when the car is turned off. I've used these a few times over the years in various cars -- simple, cheap and difficult to troubleshoot (for thiefs) on the fly...only downside -- doesn't do much about glass breaks or other types of vandalism like features found on aftermarket alarms...
Otherwise run a search -- numerous posts on Viper and other aftermarket alarm systems. You can even unplug the factory alarm module and use the harness connections there for the aftermarket system (believe Ash Powers did a post on this a while back?)....
