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.
TrayStatus - Do you have a notebook or keyboard without a NumLock or CapsLock indicator light? Do you have a computer without a hard drive activity light? If so, then TrayStatus is for you.
Platypus - Realtime server monitoring and reporting
Keyboard LEDs - Indicators for Caps Lock, and Num Lock.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
CapsLock Indicator - CapsLock Indicator is a small utility that indicates the state of the Num lock, Caps lock and Scroll lock key.