Even for me, this is a geeky post.
Search engine guru (incidentally, the t-shirt I’m wearing reads GURU across the front, but that’s neither here nor there) Boris recently told me that owning high rankings for search terms was like owning real estate. I’m not sure how that metaphor fits in (isn’t it more like owning a really big, well-placed billboard?), but obviously if your site appears in the #1 spot for a search term, it will drive traffic to your site.
I pointed out that it’s not so much like owning real estate, but like owning a houseboat. You’re all right for the moment, but things can change in a hurry.