The Cartographer plugin for Ruby makes adding Google Maps to your Rails app a breeze. Want to see how easy it is to add a map? Here's some the sample code that they provide:

 <%= gmap(:mapname=>"my_map", :width=>"50", :height=>"120") %>

 <%= gmap(:width=>"500", :height=>"500", :type=>:satellite, :point=>[-122.14944, 37.441944]) %>

 <%= gmap(:mapname=>"foo", :white_div=>{:background_color=>'black', :height=>'40'}) %>

There's more in the documentation.

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