I\'ve never seen
The fact that I have never noticed
I've never really seen a point in using it. Provides very little advantage, and might even make things harder to use.
Unless you happen to have hundreds or thousands of links, all to the same sub-directory. Then it might save you a few bytes of bandwidth.
As an afterthought, I seem to recall there being some problem with the tag in IE6. You could place them anywhere in the body, redirecting different portions of the site to different locations. This was fixed in IE7, which broke a lot of sites.