If you have younger age children you might want to check out Kids Academy on iTunes. They have some really great apps that feature activities for preschool and kindergarten, and they are FREE!
This app is great if you have little ones around. It is guaranteed to not only keep them entertained, but also keep you entertained as well. I like that it is so interactive from being able to touch animals to hear their sounds to making a flower grow in a garden. It's like everything comes to life! The karaoke is also a lot of fun and you can record your kids singing along so you can play it back for them to hear when they are done.
This app is also great for early learners. It teaches them letter recognition as well as the sounds of the letters and examples of works they appear in. I like that it's so easy to navigate that children can open the app on their own and pretty much just do it all with out any help. It keeps them entertained, but also teaches them useful information instead of just wasting their time.
Disclosure: This is a sponsored post on behalf of Kids Academy. However all thoughts and opinions stated are my own and are in no way influenced by the sponsorship.