Snarl is all about being notified of events quickly and easily. It is a free and open source monitoring application that's easy to setup, well-designed and easy-to-use.
Here are some screenshots to illustrate the features and user interface of this application:
Balloon-style global notification system for PC. Screenshot of Snarl - 763px · 477pxA large number of notification types. Screenshot of Snarl - 1280px · 800pxEasy to configure notifications. Screenshot of Snarl - 1280px · 800px