Storybird - Visual storytelling community
Manuskript - Open-source tool for writers.
Imagine Forest - Create your own story online using the Imagine Forest story creator and resources. We offer story starters, fun artwork, writing games and more for kids!
StoryMill - Developers and publishers of Mac, Win, and iOS productivity, home and office and writing software such as MacGourmet, Paperless and many more. Based in MN.
StoryJumper - StoryJumper: Publish and read children's story books.
Novelize - Novelize is an online novel writing app designed to keep authors on track.