Amazon's Kindle Worlds, the company's publishing arm for legally-sanctioned fan fiction, is expanding fast. The company announced today that it's adding seven new properties, including GI Joe, Veronica Mars, and the Pretty Little Liars spinoff Ravenswood. That brings the total number of fan fiction franchises available exclusively through Amazon up to 20.

The announcement comes on the 50th anniversary of GI Joe, which is owned by Hasbro. "Hasbro now enters a new segment of the business by embracing the concept of open-source storytelling, and officially unlocking the world of GI Joe to our fans through Amazon’s Kindle Worlds," a Hasbro executive said in a statement, suggesting megabrands are starting to recognize that fanfic is a way to connect with its most loyal customers.

Kindle Worlds protects fan fiction authors from copyright claims and allows them to make money off their work, paying them 20 to 35 percent royalties on stories that sell for around $.99 to $3.99. However, the company has been criticized for taking the soul out of fanfic, a hobby that has created intimate communities around the web.

The other four new Worlds announced today are The Abnorm Chronicles, set in the world of Marcus Sakey’s best-selling novel Brilliance; The Lizzy Gardner Files, derived from Theresa Ragan’s romantic series; and Quantum and Woody and Eternal Warrior, from the Valiant Entertainment comic properties. Amazon assures us there are many more Worlds to come.