While not a pure story creation tool, OurStory provides a platform for creating rich media timelines. Note that the "embed" code is actually under a button labeled "export"
Contributions to 50+ Web Ways To Tell a Story are licensed under a Creative Commons Attribution Share-Alike 3.0 License. This site was hosted for many years at Wikispaces.com but in 2018, they pooped their own web bed. It's been hand archived by @cogdog