I have been looking at some apps to help develop skills of our low attaining children who may or may not have SEN. Of course many of the apps are beneficial and I regularly use Collins Big Cat apps and puppet pals to develop speaking and listening and basic literacy skills. Some of the apps on this page may help too.

This crowd-sourced answergarden here has some apps that others have found successful. You can also find 5 great apps for autism and communication here by Jayne Clare.

Please note, this page is a work-in-progress. I will add more as I have time!

Visual memory skills

My children have enjoyed playing this interactive pairs game in their small group. The benefits from using real cards are that it is accessible in seconds and needs no setting up. It's free too! 

Memory matches and Memory Matches 2 offer the same skills and are also free, though do have in-app purchase options.

This is what they say about their app Somantics is a suite of applications that use touch, gesture and camera input to encourage, capture and amplify the interests of young people with Autistic Spectrum Conditions and other related communication difficulties. 
Thanks for sharing Melissa of WEINS.

Clicker grids 

I have recently reviewed this app here and would also like to point you in the direction of Ant's post Clicker sentences
It costs £18.99, but is a valuable app to promote writing - and to enable children to see themselves as successful writers.