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/