CHILDREN WELCOME HERE. That’s a sign you might hang on your front door. Isn’t it a natural human instinct to want to protect our children? In this economy, though, many are “latchkey kids” or home alone because their single parent has to run to the store. If your heart is open enough and your temperament calm enough, you can provide a safe haven for the neighborhood kids. Tell parents that you have Band-Aids for scraped knees, “homework help” for the teen who needs an excuse to avoid peer pressure, time to talk and a reassuring cookie when something scares a child whose parent won’t be home from work for a little while. You might even have a small library of children’s books and a comfy beanbag for curling up to read. The idea is not to be a free baby-sitter or supplant the parents’ role but just to extend and nurture the family, even if you’re available only for a few afternoons a week and for emergencies. Your reward will come next Halloween, when your house is not (or is) tee-peed.