NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
LepideAuditor for Active Directory - LepideAuditor for Active Directory is said to be the must-have part of the IT environment and IT administration purpose.
Zohno Z-Term - The Easy-to-Use Active Directory User Termination Tool
Crowd Vox - Crowd Vox is a secured, robust, fully configurable, and customizable review script that helps you to create feature-rich business directories.
Server Density - Trusted monitoring built by experts.
OpenLDAP - OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.