Google has launched a free service called Lively, which is similar to Second Life and serves as a chat and social networking community. The difference is that the communication in this community mimics face-to-face conversations in real life. Although I haven't used it, I've seen some screenshots. This is essentially the web-based version of 3D games. In the future, you won't need to install any game discs for online games; you can just download plugins and open your browser.
In Lively, you can set up your personal avatar and decorate your personal room. You can also make specific sounds (such as laughter or crying), perform specific actions (like hugging or kissing), or display certain expressions (such as sadness or happiness).