I just found this great post about how OPML could be used to extend the great work Amazon (or other services) already does trying to work out what matters to you. It's funny though how the blogoshere works, I found the post via another post that basically summarized it. So I will link to both!
The original post I found at Mark's blog
Lisa's post - the actual subject of all this cross linking.
The original post I found at Mark's blog
Lisa's post - the actual subject of all this cross linking.