GeoKit is a Rails plugin for building location-based apps. It provides geocoding, location finders, and distance calculation in one cohesive package. If you have any tables with latitude/longitude columns in your database, or if you every wanted to easily query for “all the stores within a 50 mile radius,” then GeoKit is for you. For more information, see the GeoKit page at RubyForge.
Author: Andre Lewis
Installation:
ruby script/plugin install svn://rubyforge.org/var/svn/geokit/trunk