let's hope I manage to get this working as well both online and offline:-)

Index.spark.html

<content name="script">
  <script type="text/coffeescript">

    $().ready ->
      $("*[data-uri]").each (el) -> 
        rendertemplate = Tempo.prepare(el);
        uri = el.attribute "data-uri"
        refresh = el.attribute "data-refresh"
        $.retrieveJSON  uri , {}, (data) -> 
          rendertemplate.render data
          // TODO implement refresh

  </script>
</content>

<content name="header">
  <a href="#" alt="a link">A link</a>
</content>

<content name="main">
  <h2>First POC</h2>

  <h3>recent messages</h3>

  <ul data-url="/messages/recent" data-refresh="10sec">
    <li data-template="Messages" style="display:none">
      {{Content}} - <b>{{Username}}</b>
    </li>
    <li data-template-fallback>
       Sorry, but Javascript is required !
    </li>
  </ul>

  <h3>private messages</h3>

  <ul data-url="/messages/private" data-refresh="5min">
    <li data-template="Messages" style="display:none">
      <u><b>{{Username}}</b> {{Content}} </u>
    </li>
    <li data-template-fallback>
       Sorry, but Javascript is required !
    </li>
  </ul>
</content>

MessageModule.cs

using System.Linq;
using Nancy;

namespace Org.WBOB.Web.Modules
{
    public class MessageModule : NancyModule
    {
        public MessageModule(): base("/messages")
        {
            var fakemessages = new { Messages = "Tom,Tim,Tam".Split(',').Select(x => new { Content = "Welcome " + x, Username = x }).ToList() };
            Get["/recent"] = x => Response.AsJson(fakemessages);

            Get["/private"] = x => Response.AsJson(fakemessages);
        }
    }
}