Out of all these my favourite is Digsby, for this reason. It acts like an instant messenger, the information comes to you. If some one updates Facebook or you receive an email it tells you, you don't have to navigate away from the page. You can choose which stories you want follow up. Simply removing that step of having to go to another page makes all the difference. You only have to sign up once. It's not revolutionary but I really wish say, Google had a similar toolbar option. So you can see updated news feeds, emails, news and so on. They probably do, I know they have iGoogle but that still requires the step of visting the page.
See this from Google sounds interesting but still requires the extra navigation step
Socialstream
Social Stream project
Socialstream is the result of a Google-sponsored capstone project in the Master's program at Carnegie Mellon University's Human-Computer Interaction Institute. This project was guided by three goals that built upon each other:Print this post
Initial Task: Rethink and reinvent online social networking
Refined Focus: Discover the user needs related to social networking and explore how a unified social network service can enhance their experience.
Prototype Goal: Create a system for users to seamlessly share, view, and respond to many types of social content across multiple networks.
