Apache CouchDB is a free and open source document-oriented database written in Erlang. It is a NoSQL solution designed for local replication and to scale vertically along a wide range of devices. They've been releasing various increments, but finally, they have their 1.0 release out and ready to go.

CouchDB 1.0 delivers new features and improvements including:
- Speed – writes are 300% faster for large documents;
- Microsoft Windows support;
- Authentication system – write CouchApps without having to create a user model;
- Replicator options – flexibility to use replication to make custom systems

http://couchdb.apache.org/