mongodb, couchdb, redis y ahora acabo de...
mongodb, couchdb, redis y ahora acabo de ver esto en cassandra http://cassandra.apache.org/
Cassandra is in use at Digg, Facebook, Twitter, Reddit, Rackspace, Cloudkick, Cisco, SimpleGeo, Ooyala, OpenX, and more companies that have large, active data sets. The largest production cluster has over 100 TB of data in over 150 machines