I have a son in preschool. Since I got my tablet, I found the apps from Baby Bus.
If you have an Android tablet/cellphone or ipad/iphone, these are perfect for your kids. The link in Google Play.
In general, there are super awesome also:
- truly challenging
- super intuitive for the toddlers and preschoolers
- plenty of different apps
- beautiful palette of colors
- some have option to take pictures and store in albums
- English-learning opportunities