Alexicom AAC - Communication App available for IOS (iPad & iPhone) and Android, with external switch support.
 

ChoicePad Lite is an iPad App that features Makaton symbols.

 

FreeSpeech - A pretty good free communication App.

Gabby - A cheap, yet effective communication App for the iPad, iPhone and iPad Touch

 

Grid Player - iPad App from the makers of The Grid 2, bringing their take on a communication App to the tablet market.
 

Locabulary Pro - Communication App for iPad, Android and Nintendo DS that communicates phrases from within categories and utilises location services.
 

Predictable - Communication app for the iPad/iPhone/iPod Touch that also supports switch users
 

Proloquo2Go is a well thought out, comprehensive communication app for the iPad and iPhone and now incorporating full switch support.
 

RocketKeys - The latest offering from myVoice, giving you a type and talk App with a flexible difference.

Say Hi - Free simple select and speak communication App for iPad, iPhone and iPod Touch.