title: Replace 'collection_select, :multiple => true' with multiple 'check_box' options in Rails
body: <p>How do you replace a <code>collection_select</code> (with <code>:multiple =&gt; true</code>) with a list of <code>check_box</code> options, such that there is a <code>check_box</code> option for each object in the collection?  </p>
  
  <p>Is there an <strong>elegant</strong> way to implement this using form builders (i.e. without using <code>*_tag</code> helpers)?  I'd like to lean on ActiveRecord's built in functionality as much as possible...</p>