Over the past few years, I've compiled my favorite of Google's hidden treasures into the Secrets of a Google Ninja (now a searchable database, too). And, today I was going to add Kiddle to it. However, in doing some reading, it appears it is not supported by Google. While powered by Google results, it is not supported. For products like such, I turn to Common Sense Media who does an awesome job of rating and reviewing similar sites.
For a complete directory of Google's other products, check out fennvoation.org.