Just paste a small piece of code into your site, blog, social network, etc., just any web page. And you have the Instant traffic numbers. The guys at whos.amung.us also have developed a cool Firefox plug-in, though configuring it can be a bit confusing.
You will need to copy a code(8 digit one) from the widget's HTML and paste it into the plug-in's setup window. Once it's running, however, you can monitor site traffic from Firefox's status bar. Whos.amung.us is a very nice alternative to traditional counters as it have a very flashy and simple interface.