Couchbase Lite is a nice schemaless (NoSQL) database for mobile (iOS, Android,…).
It is good for local storage and easy to use in mobile app. And it also has super feature: Ability to Syncornize to remote database (or across multiple devices).
Preparing demo for local event I configured environment for synchronization using AWS EC2 Micro instance with standard Ubuntu x64. Alternatively it could be setup locally on variety of different Unix systems.
Couchbase Server, Sync Gateway and Couchbase Lite framework can be downloaded from official site.