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.
Luupro - Get social about the projects you're working on!
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Waitlist API - Quick and easy waitlist with built in referral.
Better Uptime - We call you when your website goes down
Landing Pages in MailChimp - Easy to build, custom landing pages for free