Objectify-Appengine is a thin Java wrapper around Google App Engine's low-level datastore API that allows you to persist type-safe POJO objects. It provides a human-friendly query interface, generified key, query, and prepared query classes, GWT-able entity objects, and transactions in one lightweight jar file with no dependencies.
CaroView for the Google cloud facilitates online map creation and publishing of geo-content from fusion tables and other online sources and services You can configure, author, and publish your map from the browser, with no programming required. It will render your geodata from Google fusion tables and external sources (GeoRSS, KML, or ArcGIS Server). You can select from a large number of plugins to use in your map: Twitter, Yelp, events, weather, and many more.
Vikuit is an advanced social networking engine optimized for Google App Engine. It aims to possess every feature for a social network engine while remaining easy to deploy and manage. It is built with Python and is focused on running on Google App Engine (GAE). Vikuit is intended to fill the gap between software-as-a-service platforms like Ning and on-site deployments. Its key features include articles and news, support for multiple languages, groups, Google native authentication, microbloging, following a user, profiles and profile comments, comments, photo galleries, full searching, user dashboard, and recent activity. For developers, Vikuit uses themes based on jinja templates and special modules, called Vikuitlets, that provide an easy way to extend it.