Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
PingCastle - Because the Active Directory security lies in the process and not in expensive tools, our solution is simple: download PingCastle and apply its methodology.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Sysmalogic AD Report Builder - Active Directory Report and Scheduler Quickly find AD info to match your clipboard content
Better Uptime - We call you when your website goes down
ManageEngine ADAudit - ManageEngine ADAudit is a real-time windows active directory auditing tool.