Peggy Marcy suggested this site, Storybird. You can create a story using art from various artists. There are many story creation sites, but I like this one because of the art. Different artists post a collection of work here, and you can choose one to illustrate your story. Some of the art is charming, and some is quite beautiful.
My story is for young children, but I imagine your students could get as complex as their language ability allows. My story is about a hungry bear. If your students create a Storybird, please post a link here to share.
Here are some other examples:
A princess who collects too many pets. Learning life's lessons