title: Get zip code based on lat & long?
body: <p>Is there a service or API I can ping, and pass in the lat/long as parameters, where it returns the zip code that lat/long pair is within? This is US-only, so I don't have to worry about international codes, etc.</p>
  
  <p>I feel like Google Maps' reverse-geocoding is too heavy for me. I'd prefer something lighter, if possible. This will be done in javascript.</p>