I glanced out the window as I was making lunch today and noticed my neighbor and her baby getting dropped off. Several minutes later I glanced out again and saw that they were standing at their front door. None of their cars were in the driveway, so I figured she must have been locked out.
I stepped out to the porch, hollered across the street to confirm my suspicion, then invited them to wait at our house. She left her locked door and came through our open door.
I met this neighbor once when she answered the door for one of our monthly "take goodies to the neighbors" outings, but her brother comes over somewhat regularly, her youngest sisters came periodically during the summer, and I've chatted with her mom very briefly a couple times. We have a neighborly acquaintance kind of relationship with their family, but nothing more.
Anyway, we were able to give her daughter some food, our bigs bombarded her with questions and talked her ear off while I took care of some household stuff, our littlest played with her baby, then she and I chatted about homeschooling, her career plans, cooking and baking, paint colors, the local schools, having babies, and other random things.
She's a lot younger than I am and in a totally different place in life, but I thoroughly enjoyed our visit. She was here for 3 1/2 hours and we exchanged numbers before she left.
One locked door + one open door = a new friendship.