* http://nosql-database.org/
  * http://www.mongodb.org/ 
  * http://incubator.apache.org/cassandra/
  * http://project-voldemort.com/
  * http://code.google.com/p/redis/
  * http://1978th.net/tokyocabinet/, http://1978th.net/tokyotyrant/
  * http://scalien.com/keyspace/