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.
Video Live Chat for Websites - Provide real-time video chat support with screen sharing
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Better Uptime - We call you when your website goes down
Live Chat by Sumo.com - Instantly communicate with customers, prospects & visitors