If your kids are anything like mine, I rarely have my phone in my actual possession. My five-year old is particularly obsessed with Angry Birds and counting down the days until the new Angry Birds Space comes out. A great site that I contribute to is an app review site that focuses on educational and children's mobile applications. The site is called SMATOOS and the two apps I've covered include:
Baby Flash Cards by eFlashApps Review
This app is great for parents who wish to expand the vocabulary of babies and toddlers. It includes real photographs of objects and crystal clear pronunciations.
Earth Now by Jet Propulsion Laboratory Review
This app is more for kids in middle school and high school. It provides statistics on different levels in the earth's atmosphere and how the amounts of the substances are affecting the climate. Data is taken from space satellites and displayed on a 3D model of the globe.