Some are being trained as service rats.  I know of someone who has one that is trained to sense the beginning of muscle spasm and warn her before they start to take medication.  Also, personally I know that nekked rats are fantastic for people with fibromyalgia.  My cuddly boy Bug gives off so much heat it's like having a small, kissy hotwater bottle that never goes cold.

However, the rats that are being trained for landmine sweeping aren't like our pet rats.  They're African pouched rats and they are highly aggressive and not very cuddly.  They have super poweful jaws that can even chew through metal.  However, due to their high intelligence and light weight, they make excellent landmine sniffers, I just don't think I'd try kissing it on the head.