Mozilla's demo movie shows two users signed in with Browser ID (recently renamed Persona) start a video chat right in the browser.
The Persona features, combined with the Social API add-on for Firefox, make the demo browser look a bit like Facebook or other social sites with a "buddy list" of currently signed in users available in the sidebar.
You can ask a question or share a thought and you will be shown a list of people with similar interests to talk to.
Unlike other services, the user on the other end has to accept your chat request to begin the conversation.
Randomdorm is similar to the web apps listed above but is limited only to college students.
Omegle allows you to share the chat log in your Facebook account or to download it to your PC. It allows you talk to your friends or to random strangers.
The site also supports Facebook Connect, however, the email id with which you have registered in Facebook should be id. Apart from being an extremely hilarious idea, I noted a few funny things in these web apps.
For example, in the case of Chatroulette the only contact address provided is [email protected], which could well be appropriate considering the usefulness of the entire idea.
The user interface is a bit more refined and you need to have flash installed to even see how the UI looks like.
Omegle has been around for a while connecting random strangers in text chats.