etcd[1] is a distributed key-value store with some interesting properties for making things like locking mechanisms. It's like zookeeper[2] except it uses the raft consensus algorithm[3][pdf] and is written in Go.

[1]: https://github.com/coreos/etcd

[2]: http://zookeeper.apache.org/

[3]: https://ramcloud.stanford.edu/wiki/download/attachments/1137...