The new Google Reader application on Facebook is noteworthy. You can set it to display your own shared items (here are mine), someone else's shared items, or - and here's the kicker - the world's most popular shared items.
Why is that interesting?
It's all to do with the way we cut, slice and manipulate data on the web. Having just finished David Weinberger's stellar book, Everything is Miscellaneous, one gets an understanding of how we categorise information, and how that affects the human capacity to process knowledge. Weinberger talks about the Dewey Decimal System, and how that tried to make sense of a world full of atoms. Now we have tagging, which not only provides a means of categorizing assets in multiple ways, but most importantly puts the power into the hands of end users. This in turn makes the information more valuable and accessible to all of us. And shifts the power from those who own the information (such as traditional media) to those who consume it. This is not a static boundary.
Being able to view one person's shared items is certainly valuable. I follow Robert Scoble's link blog (as he calls his shared items) via RSS, and it's often more interesting than his actual blog - which I suspect he'd admit himself. I don't have time to read all the feeds Scoble reads, so it's useful to have someone siphon off what he sees as the items I might find interesting.
On the face of it, taking another cut of the Google Reader data to present the aggregation of most shared items isn't such a big deal. But for me, it's interesting on two levels; first, I get to discover interesting content that I might not otherwise had found and, second, it pushes the boundaries of information dissemination just a little bit further. And that's good for everyone.