[jlouvel]

APISpark (PaaS for APIs) is capable of creating a REST API (JSON/YAML/XML formats) on top of a Google Spreadsheet, using it as a database: http://restlet.com/technical-resources/apispark/tutorials/tu...

In the latest version, it comes with a server-side API cache to prevent GSheet latency and availability issues.

Note: I'm the founder of APISpark