Nextdoor -- http://nextdoor.com/
Nextdoor is a private social network for neighborhoods, where neighbors can talk online and help make their community better in the real world. People are using Nextdoor to find a trustworthy babysitter, organize a garage sale, ask for help locating a lost pet, and exchange many other kinds of help and information with their neighbors.
We're a venture-backed startup company of 23 people in downtown SF. We just launched our product last week, and are looking to grow with a few more key hires--particularly software engineers and product designers. If you like (some or all of) Python, jQuery, AWS, geospatial data, clean and usable design, a fast-paced startup environment, please take a look at our job opportunities, and we'd love to hear from you.