Gae free software

https://groups.google.com/group/google-appengine/web/google-app-engine-open-source-projects?pli=1

AppRocket is an open-source replication engine that synchronizes Google App Engine datastore and MySQL database.

https://github.com/k7d/approcket/wiki/

GAEO MVC Framework

http://doc.gaeo.org/tutorials/create-a-simple-guestbook-application