I'm not really sure how we missed this app when it was released way back in July, because it's damn cool. A company called Directed Electronics produces an automotive remote start kit that's called Viper SmartStart, and the kicker: it's controlled via smartphones. The app was available on iOS and BlackBerry for some time before being released for Android in July, and it's some pretty neat kit - check out the video (sorry, it won't embed because it's unlisted).
You can start your car from your house, then when you get inside your (now warm) car, you can arm the alarm on your house. You can also lock and unlock the car, unlock the trunk, trigger the panic alarm, call for help or a tow, or use it to track where the car is parked. Like I said: neat.
The app is free, but prices for the kit range from $300 to $600, so it's not exactly for the faint of heart. (Coincidentally, I've always wondered if/how remote start kits work in manual-transmission cars.) Hit up the source link for more details.
[Source: Viper SmartStart, thanks for the tip Mike Y.!]