nxlog - NXLog offers log management solutions for companies of all sizes.
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.
Nagios Log Server - Nagios Log Server is centralized log management, monitoring & analysis software. Quickly & easily manage, monitor and analyze log data. Download Today!
Graylog - Graylog is an open source log management platform for collecting, indexing, and analyzing both structured and unstructured data.
Splunk - Splunk's operational intelligence platform helps unearth intelligent insights from machine data.
Fluentd - Fluentd is a cross platform open source data collection solution originally developed at Treasure Data.