CouchDB
Summary CouchDB is a schema-free document database. But now that the NoSQL movement is in full swing, there are several document databases to choose from, so why choose Couch? Two things really set CouchDB apart from the rest: its map/reduce views and its RESTful API. Since the API is RESTful, you can easily use Couch from any platform that can talk HTTP. The benefits go way beyond that, though...
