I have been toying with the idea to wire my alarm into my fuel pump or the ignition system so when the alarm goes of it will prevent the engine from running.
The only problem i see from doing this is if the alarm malfunction while driving it will shut the engine down.

 

Well you transponder in your key (If still enabled) already does this, the only way someone can start the car is to have a properly coded key.

Second, If the alarm is aftermarket, there's a high probability that any time the alarm is armed there is a starter kill that is enabled.

If you still have a factory alarm then there is no easy way that I can think of to add a starter kill without the addition of an aftermarket system. They do make alarm systems that work with the factory transmitter if you want to keep that as well.