Many hosting services say they guarantee 99% uptime. But how would you really know without checking your site every often. Pingdom is a popular web service that allows you to automate this by telling it to ping your website every specified interval (e.g. 1 minute). Based on certain settings, you can have it notify you when your site is down. You can give it a URL to a page to ping. But, don’t give it your home page since that would inflate your Google Analytics (or other statistics software) home page visit count. Instead, specify a URL to a unlinked page like http://www.yoursite.com/pingtest.htm