I'd found this comparison of Zookeeper, etcd and Doozer:
http://devo.ps/blog/zookeeper-vs-doozer-vs-etcd/
Serf (serfdom.io) is also a nice solution as it is simple! But you must consider, SERF is just a cluster-manager which enables you to send custom events to all cluster nodes. Thats nice, but you have to write your own shell scripts (aka events).
See this example: "https://www.digitalocean.com/community/articles/how-to-set-up-a-serf-cluster-on-several-ubuntu-vps"
The advantage is, you're getting a very simple cluster-manager and you're able to combine this with your favorite configuration, deployment or continuous integration tool.
