A javascript geocoder piggybacked on the GeoDjango Admin Project

geocoder.js

{% block extrastyle %}
<style type="text/css">
  #{{ id }}_map { width: {{ map_width }}px; height: {{ map_height }}px; }
  #{{ id }}_map .aligned label { float:inherit; }
  #{{ id }}_admin_map { position: relative; vertical-align: top; float: {{ LANGUAGE_BIDI|yesno:"right,left" }}; }
  {% if not display_wkt %}#{{ id }} { display: none; }{% endif %}
  .olControlEditingToolbar .olControlModifyFeatureItemActive { 
     background-image: url("{{ ADMIN_MEDIA_PREFIX }}img/gis/move_vertex_on.png");
     background-repeat: no-repeat;
  }
  .olControlEditingToolbar .olControlModifyFeatureItemInactive { 
     background-image: url("{{ ADMIN_MEDIA_PREFIX }}img/gis/move_vertex_off.png");
     background-repeat: no-repeat;
  }
</style>
<!--[if IE]>
<style type="text/css">
  /* This fixes the mouse offset issues in IE. */
  #{{ id }}_admin_map { position: static; vertical-align: top; }
  /* `font-size: 0` fixes the 1px border between tiles, but borks LayerSwitcher.
      Thus, this is disabled until a better fix is found.
  #{{ id }}_map { width: {{ map_width }}px; height: {{ map_height }}px; font-size: 0; } */
</style>
<![endif]-->
{% endblock %}
<span id="{{ id }}_admin_map">

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"> </script>

<script type="text/javascript">
//<![CDATA[
{% block openlayers %}{% include "gis/admin/openlayers.js" %}{% endblock %}
//]]>

var geoCodeURL = "http://nominatim.openstreetmap.org/search?format=json&q=";

var zoomToPlace = function() {
   var address = document.getElementsByName("geocoder")[0].value;
   if (!address)
      alert("Please type an address or location!");
   else {
       $.ajax({
              type: "POST",
              dataType: 'json',
              url: geoCodeURL + encodeURI(address),
              error: function(jqXHR, textStatus, errorThrown){
                alert('error: ' + textStatus + ' ' + errorThrown);
              },
              success: function (response, textStatus, XMLHttpRequest) {
                  //console.log(response);
                  if (!response.length) {
                     alert('geocoder did not return any records');
                  } else {
                      // zoom to first returned
                      var lon = response[0].lon;
                      var lat = response[0].lat;
                      {{ module }}.map.setCenter(
                         new OpenLayers.LonLat( lon, lat).transform(
                            new OpenLayers.Projection("EPSG:4326"),
                            {{ module }}.map.getProjectionObject()
                         ), 13);
                  }
              }
        });
  };
}

</script>

<p>zoom to address:
<input id="{{ id }}_geocoder" name="geocoder" value="">
<button type="button" onclick="zoomToPlace()" >Geo-code!</button>
</p>

<div id="{{ id }}_map"{% if LANGUAGE_BIDI %} dir="ltr"{% endif %}></div>
<a href="javascript:{{ module }}.clearFeatures()">Delete all Features</a>

{% if display_wkt %}<p> WKT debugging window:</p>{% endif %}
<textarea id="{{ id }}" class="vWKTField required" cols="150" rows="10" name="{{ name }}">{{ wkt }}</textarea>
<script type="text/javascript">{% block init_function %}{{ module }}.init();{% endblock %}</script>
</span>