$.extend({
	nav : {
		toggle : function(obj)
		{
			var t = $(obj);
			var open = /\/plus\.\w+$/.test(t.attr('src'));			
			
			var icon = open ? 'minus' : 'plus';
			t.attr('src', t.attr('src').replace(/([^\.\/]+)(\.\w+$)/, icon+'$2'));			
			
			var list = t.parent().next().children('div');
			list.slideToggle('slow');
		}
	}
});