Interesting post!
I volunteer with young people with autism and, while our projects don't involve computers/technology as such (they are more activity-based, focussing on social development), one of my never-get-around-to projects is to look into app development for SEN. Either way, i'm always interested in hearing how people approach design for children/education.
Pinterest is good for finding examples and a lot of teachers use it to share materials. Some of these will be digital apps. I use it to pin examples of drag and drop coding/design aimed at children.
I don't have kids to give a parents' perspective, but one of the young people I support uses an iPad app at home that lets him watch YouTube videos without supervision and empowers him to choose - from a pre defined playlist his parents have created - what he wants to watch. I think it's iTubeList (
http://ipadkids.com/itubelist-review-take-control-of-youtube/), although the review there isn't particularly favourable.
On our last project we also used a music app that let the young people play instruments like flutes and drums by touching the iPad screen. There are lots of these apps around and they are not necessarily aimed at children, but it was so tactile and intuitive that the technology didn't get in the way of the fun we were trying to achieve in the workshop.
I think any software targeted at kids needs to strike the balance between providing a safe environment for the child to play/learn, while not dumbing down the experience. An intuitive user interface, parental controls and age-appropriate content, and privacy settings for any social media interaction would be my considerations.