I was just thinking this. When I pass a URL to a buddy like this one:
http://www.rockymountainnews.com/news/2008/may/30/space-alien-video-surfaces-in-denver/
Even if my friend is super busy, he'll probably say, "Holy crap, what is that?" and click on it.
That URL is much better than:
Picking on FOXNews and Venette: http://www.foxnews.com/story/0,2933,360941,00.html
Denver Post: http://origin.denverpost.com/ci_9427587
ABC News: http://www.abcnews.go.com/US/comments?type=Story&id=4957753
None of these links compels the recipient to click on them. My busy friend will probably think, "Oh, another link from Eric... I'll look at that in a few minutes." Then he continues and probably forgets about the link.
So when we're writing slugs, we should definitely think of them as important and eye grabbing as a headline. Every little bit helps to get those clicks.
Now, Rocky Mountain News isn't immune to this, The URL I used above was fabricated. The actual URL is:
http://www.rockymountainnews.com/news/2008/may/30/alien-commission-causes-commotion/