Think of it as fire-and-forget ammo for those afflicted with "I am my brother's keeper" syndrome.
Splogbane: If you are reading this on a blog other than http://blogs.technet.com/tonyso, why not stop patronizing a splog and come over to the original?
Marcus Anthony and Scott Bullens have a startup that makes me sad/glad. Sad we need it, glad it is there. My Mobile Witness allows you to use the camera in your phone and text messaging to send a photo of someone (or, say a license plate) that can be retrieved by law enforcement without a warrant. This can be a powerful deterrent.
Say a friend leaves a party with a person they've just met against your advice and having had too much to drink. You snap their pic and inform them you expect your friend to get home safely, if they don't the authorities will have the info they need to follow up.
The service is free - but there will be ad-support in their somewhere I'm sure.