The Geokit gem provides:
- Distance calculations between two points on the earth. Calculate the distance
  in miles, kilometers, meters, or nautical miles, with all the trigonometry
  abstracted away by Geokit.
- Geocoding from multiple providers. It supports Google, Yahoo, Geocoder.us, and
  Geocoder.ca geocoders, and others. It provides a uniform response structure
  from all of them. It also provides a fail-over mechanism, in case your input
  fails to geocode in one service.
- Rectangular bounds calculations: is a point within a given rectangular bounds?
- Heading and midpoint calculations