I just created the following logic on my phone to preserve battery life. Yes, I am a nerd, but having the flexibility to be this nerdy is awesome. :)
This was created using a cool app called Automate It, which allows you to create all sorts of custom rules and logic. I use it to automatically enable GPS with specific apps, trigger events like a FourSquare check-in using NFC, all sorts of fun.
Oh.. I also created the flow chart (using MindJet Maps) and created this post all on my phone.
For the win!