You might find it handy to use a service than can monitor/watch/scan to see if your websites are up and running, so that you don’t need to check your website every hours.

I have found a couple of free alternatives:
http://basicstate.com/
http://www.montastic.com/

– If you only have 1 website or need to have a really throrough monitoring service, which checks your website from MANY locations accross the world, you might want to look into some paid service such as: http://www.serviceuptime.com/free_monitoring.php

These services also monitors website uptime:
http://www.siteuptime.com/
http://www.digicure.dk/instantalarm.html

And one website monitoring service in Danish:
http://www.digicure.dk/instantalarm.html

This service for cheking your website uptime and getting reports (sms and email alrts) by downtime is in several languages and has as paid a s well as free service:
http://www.hyperspin.com