Storybird is an absolutely amazing interactive site. Storybird is a very user-friendly way of combining pictures or drawings and text to tell a story, and then share that story with other people.
You choose images from a huge bank of ready-drawn pictures which also help to provide inspiration for story ideas. The site is very easy to navigate and writing a story is a snap. To write a story you have to create an account but it's super easy and it's free!
One of the greatest things about Storybird is that you can have several students all work on the same story together. Once you are done creating a story, you can either send it to others or embed it into a blog or website. There is a huge library of stories created by others that you can read to get inspiration for your own story.