I've commented before that Friend Feed makes for a really sweet Twitter client because of the way it threads replies and how easy it is to reply to another user. The only problem is trying to find all of your Twitter contacts on Friend Feed.
My best guess is that I want Twine's technology, FriendFeed's interface and the ability to import my friends from all of my other social services (probably Twine's biggest drawback). If someone provides all of this, they could be the next Google.