Consul

Main Stuff
Service Discovery - provide a service or find a service
Health Checking - to avoid unhealthy nodes
Key/Value Store - includes a hierarchical kvs
Multi DataCenter - yay high availability

Architecture
Service provider runs a Consul Agent
Consul Agent talks to a Consul Server
Consul Server can run/should in a cluster.
Recommended one cluster per datacenter.
Don't need to run a Consul Agent to find a service provider.

from http://www.consul.io/intro/

Very nice compare/contrast of Consul vs various other tools.
http://www.consul.io/intro/vs/index.html