Besides of the above URL, http://downforeveryoneorjustme.com/ works not only for google but any other service too. However, I got suggested that tool via twitter, but I have no clue how it works or how reliably it is.
"Looks down from here" suggests to me that it's simply doing an HTTP GET and interpreting the returned status code (or timing out). http://downforyouaswellorjustme.com/ would probably be more accurate.
right. Even better the service could become if they'd watch the status pages for the services they'dget asked about. But takes a little more effort than a plain GET.
I didn't know that such a google-page actually exists, thanks. btw: gmail works for me at the moment (although its status is marked with "Service outage").