Loggr - Loggr offers cloud-based, real-time Web Application Monitoring, which includes monitoring application events and users with ad-hoc analytics and notification system.
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.
pgBadger - pgBadger is a PostgreSQL log analyzer.
Grafana - Data visualization & Monitoring with support for Graphite, InfluxDB, Prometheus, Elasticsearch and many more databases
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.
Circonus - Circonus combines multiple monitoring, alerting, event processing, and analytics tools into one unified solution.