Check this out… If you go over to montastic.com you can set up an account and enter any domains that you wish to monitor. You can enter up to 100 domains and, once it’s set up, they’ll periodically ping the sites on your list and e-mail you if there’s a change in status (i.e., site is down, site is back up).
This is a great little set-and-forget tool for alerting you to downtime so you can follow up with your host and get things straightened out. Likewise, if you’re using any affiliate programs, you might want to monitor them to protect against possible outages — this is especially valuable if you’re running pay-per-click campaigns, as downtime = wasted advertising dollars.
The monitoring can be a bit haphazard at times, in that it pings at somewhat random intervals. For example, of the sites that I’m currently tracking, one hasn’t been pinged in four hours whereas all the others have been pinged within the past hour. Regardless, it’s free and easy to use, so you have nothing to lose by setting it up — this is especially true if you use any sort of “budget” web host.