Mentat - Persistent, relational store inspired by Datomic and DataScript.
RocksDB - Persistent Key-Value Store for Flash and RAM Storage.
goleveldb - LevelDB key/value database in Go.
Noria - Dynamically changing, partially-stateful data-flow for web application backends.
RethinkDB - Pushes JSON to your apps in realtime.
RedixDB - Persistent real-time key-value store, with the same redis protocol with powerful features.