Welcome to the Internet Weather Map 
The Internet Weather Map (IWM) is a free service that maps latency on the Internet. As an Open Community project, it uses data from volunteers all over the world to feed back latency on the Internet into a central database. Then that data is aggregated, and displayed in table and map formats, allowing you to see how the fast sections of the Internet are running. While it practically not possible to map out every segment of the entire Internet, the IWM product traces thousands of segments to give you an informed idea as to it's overall latency.
The service is divided into a number of Tabs at the top of the screen. You are on the Overview tab now, which is a description of the service. The Latency Map tab is the heart of the service, which displays a map of any delays on the Internet, as well as in a table format. While the table displays the top 25 slowest segments, the map only displays delays (latency over 500ms). The data on this tab will refresh every 60 seconds, so there is no need to re-load the page manuals. The Tools tab allows you get information on your domain name, including MX Record Lookup, and some diagnostics.

Tip: If you have a spare monitor, this screen makes an excellent reference tool to keep displayed at all times.
An example of the Latency Map is below, showing a various problems in the USA and China. Use the Latency Map for a live data feed.