I was reading an article about URLs and how they are a UI element to the whole Web experience. I use them all the time to navigate through websites. When I like a site I will usually try to guess the proper address for something else I might like in the site. For example I'll try to go up one level to the parent directory and see if there are other articles related. I'm not the only one that does this.
The discussion about using URLs as UI elements is pretty engaging, and I even found a document that shows where people look on the screen as they go through a website. It isn't new, but its pretty neat to know.
We found that searchers are particularly interested in the URL when they are assessing the credibility of a destination. If the URL looks like garbage, people are less likely to click on that search hit. On the other hand, if the URL looks like the page will address the user's question, they are more likely to click. ... the full whole thing is right here URL as UI (Jakob Nielsen's Alertbox)