I can't quite get my head around how this works or if it works, but it's an interesting take on social networking that seems to have teen appeal. Polyvore.com is combination of fashion, shopping, and social networking recently launched by a Yahoo! alum. Basically, a browser plug-in allows you to snag web images (particularly of clothes, apparently) and combine them into sets, like this:
Why do I know about this? Because Laurie Stolarz discovered that a user had made a set for Blue is for Nightmares. And there are Stephenie Meyer sets. It does not appear that anyone has made a set for Feed.