If you have an e-commerce site, it’s paramount to know if it goes down to take the proper countermeasures. Having an application running on your machine that pings the website is impractical and doesn’t work if you pc is turned off.
Much more reliable is a web monitoring service like Montastic, that pings your sites every ten minutes from two different locations and notifies you if something is wrong.
Montastic allows you to monitor up to 100 websites for free. If your server goes down it’ll send you an email. Another email is sent when the site is back up.
You can also see your sites status via RSS or using a Yahoo Widget (you can download the Yahoo Widget Engine here for free) so that you can always keep an eye on your sites.
I added three sites: my main website, my blog (which is hosted by another ISP) and my Plimus order page. I can sleep better now.