QuickMon

QuickMon is a simple monitoring and alerting tool. It allows you to monitor and alert on various resources/services locally or remotely.

Summary of functionality

Polls resources on predefined frequency
Agents use a 'plug-in' architecture
Agents are (XML) config driven - Each 'agent' can be customized on its own
Collectors can service multiple collector agents - of different types
Collector hosts returns one of three possible states: Good, Warning or error
Several different notifier agent available for alerting
Each notifier can be set up to fire on collector states - e.g. only errors/errors and warnings
Groups of resources can be monitored (and alert on) as a unit - using Monitor packs
Parent Collector host specify if child collectors get run based on specified 'Check behavior'.
Collector hosts can run as a 'different user' (impersonation)
Alerting can be customized in several ways - like suppression, delaying, repeating etc.
Resources on remote machines can be monitored via remote host functionality if direct access is blocked (e.g. firewall)
Collector agents can be set to operate only in specified 'service windows'
Collector agents can suppress/override polling frequency
Corrective scripts can be executed if collector returns error/warning
Monitor packs can be used in both a Windows client or a Windows Service
It runs on All versions of Windows that supports the .Net 4.0 framework - e.g. 10, 8, 7, Vista and even XP. Windows Server OS'es are also supported.
Linux (and any other Nix OS) can be monitored via SSH based agents using http://sshnet.codeplex.com library.