User route tracing

Logging is an old subject. It's simple just record the page requested, time, IP number and maybe the refering URL. Instantly you can draw up graphs on the most popular pages, the best referers etc. This in its own right is very useful. However, when I was looking at the logs on one of my larger sites, I thought - I know that page "x" gets so many hits a day, but the user could have come to that page using a variety of different routes. How do users get to page "x"? On some sites there is a variety of different ways to reach the same page. On PHPbuilder for example, most people probably see the list of new articles and choose one of those. How many people go to the columns page and look at all the articles? This isn't the best example but I think you get the idea. If you know this information you can see how effective your navigation system really is.