Email n' Walk lets you email and spy with your iPhone
Email n' Walk can also be used to spy on suspicious characters while looking like you're nondescriptly writing a message. Fortunately, though, it's really meant for your safety, not for stalking. You can't take or save photos from it. Email n' Walk also doesn't replace the built-in Mail app on the iPhone. When you save your message, it pops open Mail so you can address and send it.
You can pick up Email n' Walk for 99 cents in the App Store.