Checking status of websites

A while ago, someone on here (think it might've been Asa actually) mentioned a site where you can check if a website is down. It was a really handy thing, but I've completely forgotten what it is. Anyone have any idea?

Thanks,
Eoin

http://www.netcraft.com/ is the site you are probably thinking of. It tells you how busy the site is, when it is down and what kind of server it runs.

Not the same one, but just as useful.

Thanks very much

http://www.alertra.com/ is a possibility.

That's the one!

Thanks a million