There are many apps available that are fun, motivating, educational and promote speech and language development. Many of these apps are geared towards a younger population. I will try and list the apps I find that are more for upper elementary and middle school students.
Language:
Sentence Builder- helps children build grammatically correct sentences
Question Builder-helps children build grammatically correct questions
Tense Builder-helps children identify the correct tense
WhQuestions- With built-in data tracking, there are over 300 "wh" questions for who, what, where, why,how
The following apps are engaging for students and adults. I use these to develop natural conversations about a shared topic/interest.
Music
Beatbox- create your own beats
Bloom- create patterns and melodies by touching the screen
Drum Kit- create and record drum tracks as your playing along to songs
Art:
Doodle Buddy-finger paint with colors and tap the screen to include backgrounds
iColoring Book- using many colors, paint included images or use downloaded pictures from the Internet