Do you run a website or a blog, do you want to track websites going down ? You can use Ding It’s Up to get instant notification when something goes wrong.
Ding It’s Up is a free service that alerts when a website goes down or when it comes back up. The users can choose to receive the live alerts via text messaging, e-mail, or Twitter.

Several of the free website monitoring companies are similar in results if not better as compared with many of the paid monitoring services.