+1 on the toning down of your driving for the last few km's / minutes of driving.
Depending on how hard I've been driving prior to parking, I would normally let my car idle for approx 30 seconds before turning off... Sometimes a little more. After say a Nasho run, my car would be running for a good few minutes before I even think about shutting her down.
Yes there has been a lot of talk about how useful a turbo timer is on the newer turbo cars. At the end of the day, I still think it would be a useful mod & personally I'm looking at getting one in the not too distant future

Just means you don't have to think about it when your in a rush.