As a learning tool
Kids often love to be read to, even by a Laptop computer. It can prepare them to learn quickly how to read age appropriate material.
 As a learning ploy
Reading aloud trains a reader to understand the material and excercise appropriate speaking skills or even acting skills. Thus the task has multiple purposes and multiple results. Naturally, the teachers and parents can help with each objective by appropriate feedback and guidance.
 As a class project
If a class team investigates some curriculum topic, it could present the result as a vocally annotated slide show, exercising an entire spectrum of skills including cooperative working skills.
 As an application
Making an app that makes it easy to construct a slide show of book pages which emphasizes each word as it is spoken could be quite helpful. How hard can it be? One might play a few words and mark the inter-word transitions on a time line showing the audio envelope on the screen. A few rounds of adjusting the exact locations and playing the result again should be able to make the correspondence of spoken and emphasized words (color or bold or underlined or at the bouncing ball) quite good enough to help pre-literate kids get ready to learn to read, and love the process.
Hello to all
I have this already
In place Highlighting of noun and verb phrases