[http://incubator.apache.org/cassandra/ Apache Cassandra] is a highly scalable second-generation distributed database, bringing together [http://www.allthingsdistributed.com/2007/10/amazons_dynamo.html Dynamo]'s fully distributed design and [http://labs.google.com/papers/bigtable.html Bigtable]'s ColumnFamily-based data model.