At least I know my family and friends look out for my health and safety. :)
But just by seeing what another's email address, certain people can find out so much. Email address; IP address; Location; You. It's kind of a scary thought. But you need something to find out one's location by their IP address.
Also, there's the way of seducing somebody. I found out that Toad used to live in my neighborhood. He could 'still be there' and seduce me to tell him my exact location. Toad is a very nice person, but for all I know, he could be somebody totally different. Heck, the entire FFs could be totally different for all we know. Deezer could be an evil scientist plotting to rule the world while Megabyte is an eighty-year-old predator. Even Sapphira could be a man while Watoad is a woman! Well, not to be offending or anything; I'm just trying to give examples.
* Khold shivers at the thought