If you can’t get to a website, or if your company has a website or other system that you would like to know whether or not are “online”, the following tools may be of use:

• TraceRoute.org: Run the “TraceRoute” command from servers in a variety of locations to see if there is a routing problem. See TraceRoute in Shanghai.
• InternetSupervision: Check how a given URL is responding to traffic from nine locations across the planet. Including Beijing, LA, DC, Sydney, UK, etc.
• IsThisDown.com: Check if the website is working properly for others – or if it’s only offline for you.
• mon.itor.us: Free online monitoring tool to check any port on any site. SMS notification, high frequency polling, and a monitoring client that can be installed on your systems are all available as paid services.