Clicky Web Analytics is simply the best way to monitor, analyze, and react to your blog or web site's traffic in real time. Real time web analytics service means that when you login and view your stats, you are seeing up to the minute data on the traffic to your web site. Most services don't let you see what's happening "today" until the day after.
Real time data lets you react to changes in your traffic as they occur. For example, if you had an article that hit the front page of a popular site like digg.com, you would see the traffic spike in Clicky immediately, along with links back to the sources sending you the traffic. Knowing this, you could make changes to your site or to the article itself to take advantage of the situation.
If instead you relied solely on a service like Google Analytics, it would be up to 24 hours before you even knew about the traffic, and by then it would be too late to do anything about it.