Web 2.0 complemented with Social networking has been responsible for a plethora of web applications of unique nature in the near past. Various frameworks, technologies and protocols have emerged to support this trend. Even the server technologies are emerging to support the movement (e.g. by solving the scalability issue with cloud computing).
Open standards like OAuth, OpenID etc. have paved way in this direction by enabling inter-operation among web applications an established technology rather than an idea pursued differently by different apps. Still the implementations vary depending on the nature of apps.
All of this comes down to USER POWER, where the user is given precedence over the applications. User's profile, image, credibility is carried over from application to application spanning a network of user-app with a two-way directed graph. Combine this user-app set with your browser and you are ready to get a smooth experience resulting in YOU seamlessly using applications throughout the world connected via internet, be it services, social networks, email, forums, blogs, business apps or your own creation.