Pingdom, a site monitoring service, is offering free 1-year accounts (a $120 value) to everyone who signs up within the next 9 hours, as of the time of this post.

The free account allows you to monitor upto 5 sites, and you get 20 SMS credits. I just signed up, and although it hasn't collected any statistics yet, the control panel looks pretty good.

You don't need to provide credit card details during sign-up, so you don't have to worry about being charged if you forget to cancel in a year. Check it out if you maintain any blogs/sites that you want to monitor.