I came across a good blog the other day by David Merrill from earlier this year. In it he talks about how much sites lose per hour they are down. It is amazing. Larger eCommerce sites lose $600,000 per hour of downtime. The average company loses $100,000 for every hour of downtime. Even a bank loses $14,500 in JUST ATM SERVICE FEES for every hour of downtime.
This shows clearly how much the web is a part of our every day life and how every second of uptime is vital. It is imperative to know immediately if your website is slow or down.