Apps Run something when phone's shutting down?

[RDKamikaze]

I'm working on an app idea that I think would be very helpful but I'm having an issue finding a way to have processes run while the phone is getting ready to shutdown. It needs to be able to run for about 30 seconds once it detects a phone's going to turn off, any ideas?

Another thought it maybe having the app initiate once the battery gets to a certain level. I'm sure there's a way to have that happen but is it really hard or just a matter of having the phone call the battery life?

Thanks for the help so far!