Rating System for SharePoint Foundation 2013
The Rating System for SharePoint Foundation 2013 has been migrated "as is". Upgrading your 2010 databases should work just fine with this new version.
Two SharePoint-Hosted Apps
1) REST API Demo showing how to use the REST API to do things such as microblogging, CRUD operations on list items, creating sites, lists, security groups, performing search queries etc...
2) Content Type Explorer App helping to find by which lists and/or child content types a given content type is used.
On top of these Apps, you can find a wrapper (Farm Solution) that leverages AppFabric for custom caching in SharePoint 2013.