Write & Improve is the best way to improve your written English outside the classroom. Just choose a task and write about the topic. Submit your work and Write & Improve will award you a Common European Framework of Reference (CEFR) level, so you can see your progress.
I think that it would be good for pre-reading activities (eg. predicting, introduction of vocab etc). It may also be good for writing if you give students the words and they have to make a story from them... It could be a game...first team to write a paragraph, story (correctly), using the most words etc...
Fun, fun, Fun!