Hazelcast - Clustering and highly scalable data distribution platform for Java
Fluentd - Fluentd is a cross platform open source data collection solution originally developed at Treasure Data.
Apache Storm - Apache Storm is a free and open source distributed realtime computation system.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
Splunk - Splunk's operational intelligence platform helps unearth intelligent insights from machine data.