Opbeat - Application monitoring for developers
Redsmin - All-in-One GUI for Redis. Thightly crafted developer oriented, online real-time monitoring and administration service for Redis.
AppSignal - We monitor the software that makes your customers happy.
usql - Universal command-line interface for SQL databases
NewRelic - New Relic is a Software Analytics company that makes sense of billions of metrics across millions of apps. We help the people who build modern software understand the stories their data is trying to tell them.
Errbit - The open source error catcher that's Airbrake API compliant