Our websites are like shops and just like shops they earn no money when customers can not get in.
I came across a service that will monitor your site and send either an SMS or an email when a website stops working and another message when the site springs back to life.

The service is free of charge and they promise to not use your email address for anything other than site notifications. I do not know how often they ping sites on their list but as an alternative to my current service that works well but sends me a metric shedload of sellymails I think this is worth a look.

The URL of this service: Ding It’s UP! Site up monitor