Pixteller

With Pixteller teachers can create images, banners, posters and greeting cards. It's pretty friendly to use. There are ready made templates that your students can just edit.

This is a tutorial

Application in the classroom:

Pixteller can be useful after a reading assignment, students can create a book cover, they can create posters about the different characters in the story, send birthday cards, can write their own short poems, etc. 
Can you think of other ideas? Please write a comment.