The beginnings of advanced search for Shopify. Using javascript to update the 'type' input field. Using Shopify's search filters (http://wiki.shopify.com/Admin_search#Searching_only_for_certain_types) you can go much further. This could probably be written cleaner/faster, but this is just a quick proof of concept.

Shopify Advanced Search

<form>
  <h3>Search by type</h3>
	<input type="checkbox" id="all" onchange="searchType('all')" /> All<br />
	<input type="checkbox" id="product" onchange="searchType('product')" /> Product<br />
	<input type="checkbox" id="article" onchange="searchType('article')" /> Blog Post<br />
	<input type="checkbox" id="page" onchange="searchType('page')" /> Page<br />
</form>

<form id="search-form" name="search" action="/search">
	<input type="text" id="type" name="type" value="" />
	<input type="text" id="q" name="q" value="" class="search replace" title="Search" />
	<input type="submit" class="btn" id="search-submit" alt="Search" class="submit" value="Search" />
</form>     

<script type="text/javascript">
	function searchType(type) {
		if(type=='all') {
			document.getElementById('product').checked=false;
			document.getElementById('article').checked=false;
			document.getElementById('page').checked=false;
			document.getElementById('type').value='';
		} else {
			document.getElementById('all').checked='';
			var product = document.getElementById('product').checked;
			var article = document.getElementById('article').checked;
			var page = document.getElementById('page').checked;
			if(product==true && article==true && page==true) {document.getElementById('type').value='';}
			else if(product==true && article==true && page==false) {document.getElementById('type').value='product,article';}
			else if(product==true && article==false && page==true) {document.getElementById('type').value='product,page';}
			else if(product==true && article==false && page==false) {document.getElementById('type').value='product';}
			else if(product==false && article==true && page==true) {document.getElementById('type').value='article,page';}
			else if(product==false && article==true && page==false) {document.getElementById('type').value='article';}
			else if(product==false && article==false && page==true) {document.getElementById('type').value='page';}
			else if(product==false && article==false && page==false) {document.getElementById('type').value='';}
		}
	}
</script>