Quick and dirty way to add search to a site.

Site Search Form

<form action="http://www.google.com/search" method="get">
  <div>
    <label for="q">Search</label>
    <input type="text" name="q" value="" id="q">
    <input type="hidden" value="yourdomain.com" name="sitesearch">
  </div>
</form>