Hey, I was thinking, would this be possible to create as an app, or would it have to somehow be part of the OS?

I tried out a program where you can shut off the screen manually. Unfortunately it didn't work on my Treo. But I was thinking, how cool would it be if there would be a setting where you could: choose to turn off the screen after X number of minutes on a call, between X PM and X AM. And then when the call is over, or you turn the screen on to hang up, you have a summary of the phone call (time started, ended, mminutes used).

I say having the ability to turn off after X PM and X AM is because when you use your phone during your 'daytime' minutes, you like to really be vigilant about how many minutes you use (at least I do). At night, when you have anytime minutes, it doesn't really matter. The summary at the end, though, would be nice to know how long you blabbed, even if it doesn't count towards your quota. Cause when I'm on the phone after 7pm, sometimes I'm REALLY on the phone - like 1 hour. Having a screen that shuts off after a few minutes would really save battery life, I think.

Would this be possible to write as an app, or would it somehow have to be integrated into the OS?

Any thoughts on this?