Jq-autocomplete is a project mainly written in JavaScript, it's free.
autocomplete plugin
to use with rails 3
Download the plugin in the public/javascript git clone [email protected]:olvap/jq-autocomplete.git
include the javascript <%= javascript_include_tag('jq-autocomplete/autocomplete') %>
in the place where do u like to insert the text fileld remplace with
where table is the name of the models