Eli Fox-Epstein (elitheeli here) and I decided that we should build something this week, so we built Statusdot (http://statusdot.com). It's a service to provide status pages for websites (similar to status.github.com or status.37signals.com).
https://statusdot.com
It's pretty basic right now: You set up a CNAME pointing at statusdot.us for (for your 'status' subdomain), so you can access the site by going to status.yourdomain.com. You give us a URL, we do a GET request every 5, 10, 15, 30, or 90 minutes. If that request doesn't come back with a 200 response or doesn't contain a string you specify, we consider it down. We display that information on a status page, along with your twitter account and status messages you can post. (We also send you an SMS message when your site goes down.)
We've got a few more features and a ton more polish left to do, but we wanted to soft-launch to get some feedback, so right now it's free for a couple of weeks. (After that we're planning to start charging monthly.)
We'd love any feedback you can give. Would you use it? If not, why not? Is there anything we could add that would make it more useful for you?
Thanks!