How to add category and manufacturer dropdown to the magento default search?

Here is the code to add category and manufacturer / brand dropdown to the magento default search. Just replace your "template/catalogsearch/form.mini.phtml" with the below code.

<?php
$category = Mage::getModel('catalog/category');
if(is_object(Mage::registry('current_category'))){
    $current_category_path=Mage::registry('current_category')->getPathIds();
}else{
    $current_category_path = array();
}
$category->load(Mage::app()->getStore()->getRootCategoryId());
$children_string = $category->getChildren();
$children = explode(',',$children_string);
$extra_options='';
foreach($children as $c){
    $selected = (in_array($c, $current_category_path))?'SELECTED':'';
    $extra_options.= '<option $selected . value="' . $c . '" ' . '>' . htmlspecialchars($category->load($c)->getName()) . '</option>' . "\n";
}
?>

<form id="search_mini_form" action="<?php echo $this->helper('catalogSearch')->getResultUrl() ?>" method="get">
   <fieldset>
        <legend><?php echo $this->__('Search Site') ?></legend>
        <div class="mini-search">
            <input id="search" type="text" class="input-text" name="<?php echo $this->helper('catalogSearch')->getQueryParamName() ?>" value="<?php echo $this->helper('catalogSearch')->getEscapedQueryText() ?>" />
            <select name="cat">
            <option value="">Select Category</option>
            <?= $extra_options ?>
           </select>    
           <?php $product = Mage::getModel('catalog/product');
$attributes = Mage::getResourceModel('eav/entity_attribute_collection')
->setEntityTypeFilter($product->getResource()->getTypeId())
->addFieldToFilter('attribute_code', 'manufacturer');
$attribute = $attributes->getFirstItem()->setEntity($product->getResource());
$manufacturers = $attribute->getSource()->getAllOptions(false);?>
 <select name="manufacturer" id="manufacturer" class="" title="Manufacturer" >
          <?php foreach ($manufacturers as $manufacturer): ?>
            <option value="<?php echo $manufacturer['value'] ?>"><?php echo $manufacturer['label'] ?></option>
   <?php endforeach; ?>
       </select>
           <input type="submit" value="Go" style="border: 1px solid #808080;" alt="<?php echo $this->__('Search') ?>" />
            <div id="search_autocomplete" class="search-autocomplete"></div>
           <script type="text/javascript">
            //<![CDATA[
                var searchForm = new Varien.searchForm('search_mini_form', 'search', '<?php echo $this->__('Search Entire Site...') ?>');
                searchForm.initAutocomplete('<?php echo $this->helper('catalogSearch')->getSuggestUrl() ?>', 'search_autocomplete');
            //]]>
            </script>
        </div>
    </fieldset>
</form>