One of the coolest apps I have on my phone is called iGotYa. Put in the wrong passcode on my iPhone 4 and it will take a picture of you with the front camera, save the GPS coordinates, and email both of them to an email address of my choice.
Mostly I just get pictures of myself when I mistakenly mistype the code, but the rest of the time it’s hilarious pictures of friends from an extremely unflattering, under the neck, angle. If someone were to actually steal my phone, though, they’d almost definitely try to unlock it and end up giving me a lot to go on towards finding them.
Unfortunately, due to limitations on official Apple App Store apps, iGotYa is only possible on a jailbroken iPhone. Fortunately, even the latest version of iOS is crackable via greenpois0n.
iGotYa is about $6 on Cydia (the jailbreak app store). In case you’re wondering, it’s about $6 because it’s actually priced in Euro.