I added this to one of my trackers:

<tal:block tal:condition="python:context.is_view_ok and not request.batch()">
  <p>Search did not find any results.</p>
    <ul>
      <li tal:condition="python:'@search_text' in request.form">check the spell\
ing of your search terms,</li>
      <li><a tal:attributes="href python:request.indexargs_url('issue',
                        {'@template':'search',
                        '@queryname': request.dispname or None,
                        '@old-queryname': request.dispname or None})">
          review all your search options</a>, or</li>
      <li><a href="issue?@template=item">add a new issue</a></li>
    </ul>

</tal:block>

just below the /table tag for the results table in the index page.
If a full text search is done it says to check the spelling (which will show
up in the page.html icing search box). It also provides a link to edit the
current search by displaying it in the search template. Last it provides a link
to create an issue.