Notify your users about maintenance and incidents.
Build the trustworthiness of your service. A decent e-mail notification is a great way how to let your customers know how long you'll be off. They'll be prepared and stay tuned.
Private status page with password protection.
It's revealing when support team don't have to ask dev's about updates. Share an internal status page only with your teammates thanks to password protected status page.
It's the most simple and easy monitoring app I know and it's made my daily life much easier.
I use UptimeRobot to get push notifications whenever my website goes DOWN. It's really easy and quick to set up and requires no extra changes to your website.
We strive for minimal downtime, but if something goes wrong UptimeRobot makes sure that we know about it quickly. We switched to using UptimeRobot years ago as they offered the same services we were getting from a different provider but at a fraction of the cost.
I've been using UptimeRobot for years as a cost-effective way to quickly alert me when my sites were down - and when they were back up.