Well, to answer your question, I like the simplicity of an Android app called SwanSong. It's really lightweight and is straight-to-the-point with what it does. All I have to do is enter my e-mail address (but it actually figures this out on it's own, anyway), then my phone will email me it's location right before it dies (hence "SwanSong", so I know exactly where to find my dead phone. If my phone isn't dead, I can send a text message to it (I use Google Voice) in which case it also e-mails me the phones location.